Hi Strato,
I finished the first two ranks, so I just wanted to post my replays for them.
General RemarksWow, a lot of these levels look great, and the difficulty is certainly higher than LOA. However, I'm not sure if this is supposed to be the case, but there is just way too much precision for my taste on many of these levels. For example, the very first level requires two pixel precise assignments, and IMO this is not the way any level pack should start. The pack immediately rubbed off on me the wrong way as a result.
After all, "first impressions matter," right? I don't mind pixel precision, but if there's too many then I eventually will mind and get annoyed. In the same way I don't mind hidden traps, but put too many in a row and then I will get annoyed. You can correct me if I'm wrong, but I believe there was some discussion about levels requiring pixel precision being bad design?
Also right out the gate 3 1-of-everything levels in a row. I generally like these levels, but by the third time this happened I was like, "Again? This entire rank/pack isn't going to be just levels of this type, is it?" Admittedly, I got annoyed by the third time, but don't worry, it's not you. I have myself to blame here for being irate, since I was playing through the pack at a time when I was grouchy from lack of sleep during the day. I really need to play at a time when I'm more well-rested

Bronze 7 -
Back to the cave has a precise assignment,
the bomber, as there's only one possible position that will work. You might want to consider reducing the precision there.
Bronze 15 -
Fly on the wings of Lem might had been self-inflicted, and if so that's the blame I put on myself. I have a very bad tendency to get sucked into very fiddly solutions. Then again, two of my contest levels have a lot of precision too but with a constructive skill. Hear me disparage those who make levels with too much precision

However, I have to ask if
The first updraft the worker lemming gets to being low to be able to glide upwards is intended. Also, I find it really interesting that the jumper hoisted on the edge of the red shovel like that.
Another huge offender on pixel precision is Bronze 17 -
Bad Moon RisingAt least in my solution, RR fiddling seems absolutely necessary and delaying any who get through with shimmiers to avoid any splatting. Not to mention there are 3 very precise digger assignments here.
Bronze 17 -
Walking on the moon is another with very precise assignments, though in this case it's understandable
As setting up the route for a shimmier with builders is always quite precise. I myself made a contest level where I often got frustrated when the shimmier wouldn't keep going when I expected it to.
Bronze 23 -
Lembada has 3 very precise assignments.
Bronze 25 -
Anywhere in the galaxy is yet another level with a very precise skill assignment.
There is only one possible position for the jumper to clear the gap when it pops out of the receiver. You might want to allow more leeway there.
Finally, both Silver 9 -
Bloodhound and Silver 12 -
Counting Stars have a very precise skill (same skill in both cases, interestingly enough) assignment, but in both cases, you're forgiven, since they are integral to the solution. In the latter case, I think I understand this is necessary, as the level wouldn't look as great with maybe the entrance a bit higher.
So yea, that's quite a list. Not necessarily a bad thing in terms of difficulty, as we all know there's a difference between puzzle difficulty vs execution difficulty. Those with pixel precision assignments aren't necessarily hard levels, for example.
Bronze Rank FeedbackI didn't find any of these too difficult for the first rank. I guess to you that's not surprising to hear this

However, I believe I was a dummy on Bronze 20 -
Blue Monday the longest, with maybe either Bronze 18 -
The Lem-Catcher's Song and Bronze 30 -
Summer Night City close seconds for longest before I solved them. I don't know if there's supposed to be a lot of precision needed for the final Bronze level, and even if it doesn't, it's still a level quite worthy of that position, as I certainly think it's the hardest level of the rank, but by hardest meaning comparatively speaking to the rest of the rank. I didn't find it overly hard, just annoying to execute only to see stuff fail by a pixel or two

My favorites in the rank are Bronze 4 -
Jump around, Bronze 5 -
Highland Lemmy, Bronze 16 -
Bonny Portmore, and Bronze 18. Even though there is a precise skill assignment in the level, the main trick required in the last one is really neat, and I think you might be right about the level being harder without the fire trap.
I like Bronze 27 -
A hard day's knight due to the title referencing a Beatles song. I absolutely love the band, and I even took a college course on The Beatles. Before I took the course, I had practically the entire catalogue of songs memorized. It's been a while since I've listened to any of their songs, though, and so I definitely have forgotten a lot of them. While this level doesn't fall in the realm of pixel precision, it is one of those types of levels that I'm not a fan of due to how you have to spam a lot of skills repeatedly to save enough lemmings while the path is being forged. The solution is cool, though.
Levels that I'm sure I backrouted so badly: Bronze 6 -
Walpurgisnacht (didn't use the updrafts), Bronze 12 -
Norrsken (many skills leftover), and Bronze 29 -
Footsteps in the snow (several skills leftover).
Silver Rank FeedbackAlthough this rank is currently incomplete in the demo, I like these levels far more than the completed Bronze rank, probably because there wasn't as many levels with very precise skill assignments (only two so far compared to the many I listed for the Bronze rank above). I assume this will continue to hold when I eventually play the completed Silver rank when available.
My favorites of the rank were Silver 1 -
Let's get it started, Silver 3 -
Sippin' on Bacardi Rum (the level looks really good and I really love the solution, especially watching the glider use the updrafts on the far right), Silver 4 -
Wild frontier (really love the design [green is my favorite color, so the Outdoors tribe is one of my favorites visually] and the puzzle is great too

), Silver 6 -
Inside the pyramid of light (nice design and challenging puzzle which was satisfying to solve), Silver 8 -
Being for the benefit of Mr. Kite (level title refers to the Beatles song of the same name and the solution is awesome), Silver 9 -
Bloodhound, Silver 11 -
The mad piper (really awesome puzzle/solution), and Silver 13 -
Can you feel the Lems tonight? (I love the Elton John song it refers to and I like his songs a lot, it's a really awesome solution despite being repetitive in the skill assignments, not to mention I was stuck here the longest due to falling for a trap here

). See, this list of favorites is far longer than what I listed for the Bronze rank

Re Silver 8 - That's an awesome trick with using a shimmier jump to bomb through the ceiling so that you can jump into the water

Re Silver 9 - That's so awesome with the shimmier being able to get past the terrain despite it being above it. This is something new I learned, as I didn't know they can do that.
Re Silver 13 - For a long time I kept thinking the entire bottom entrance had to be one group of climbers/shimmiers, while the remaining 15 had to be the swimmers. However, here I ran into the problem of using a lemming from the top entrance to bash through the OWW and as a result I wouldn't have enough swimmers for the rest of them (at least 1 short). I kept trying to make it work, until I realized it needed to be the other way around: The entire top entrance are the climbers/shimmiers and the rest swimmers. Really nice difficult puzzle and design which makes you think the solution should be this way, but in reality it's actually another

Levels which I backrouted/think I backrouted: Silver 5 -
A night like this (despite having a few skills leftover, it felt hackish), Silver 7 -
What a wonderful world (it only "feels" like I backrouted it, though at the same time this seems more or less intended), Silver 10 -
When the night comes (severe backroute here), Silver 13 (I think it's a backroute, due to how I have a builder and some shimmiers left, but mostly the builder leftover is what I suspect makes my solution a backroute), Silver 14 -
The gang's all here (biggest backroute I've ever seen, way too many skills leftover

), and Silver 15 -
Atemlos durch die Nacht (slight backroute I think?)
Just to be clear, this is a great pack and has a lot of potential being a step up from your LOA pack, it's just made worse by how there's a lot of levels with unnecessary pixel precision. I think this is the first time I've seen this from you, actually, in any of your packs. Before playing this pack, all of Gigalem's packs I've played for older NL versions have a lot of pixel precision in the solutions, which definitely tipped me off because there was too much for my taste. His are similar to yours in that the levels are extremely artistic and very well-designed, but again due to the pixel precision needed that's what makes the quality of the levels suffer. Sure, some of your earlier packs had precision as well, just not to the extreme degree that I've seen so far with your HoF demo.
And of course, I'm sure patching up the backroutes for the levels I've listed will make this pack even better. Surely some of the levels shouldn't be THAT easy?
I will continue with the final two ranks soon and come back with more replays/feedback for the rest later