Mesmerizing
Intended!

Mirror World
There's a minor difference between my solution and yours, but yours is perfectly acceptable too.

In the Rear with the Gear
Intended!

Down the Rabbit Hole
This one I may call a backroute.

Terrarium
Acceptable solution! I'll attach my talisman solution below!

The Chosen One
Perfect solution! Yeah, the skillset is a bit unusual. When I made the level, I first chose several skills and limited myself to using only those, and then tried to find interesting interactions between skill types that don't normally interact much.

Mirror World
I'd consider both your solution and Dexter's acceptable.   The main idea I had in mind for this level was figuring out how to make a splatform with two builders so that the crowds from both sides can land safely. I'll attach my solution below.

The trigger areas of exits(and most other objects) have fixed relative positions. Because of that, rotating/flipping/inverting them can sometimes make the trigger areas look visually odd. That's why people usually avoid things like inverted traps or water except for aesthetic purposes, at least not in ways where the unusual trigger areas affect the solution.

That said, if someone asked me "Should a shimmiering lemming be able to use an exit attached to the ceiling he's shimmiering along?" my answer would be yes becuase it looks so natural! And in the same way, a shimmiering lemming can press a button attached to the ceiling.

The Chosen One
Good luck with this level! Let me know if you'd like a hint.

01_The_Bad_Beginning
It's an auto-level, just like the original first level of Pimolem. The path the lemmings take forming the letters 'L', 'E', 'M' is a nice little touch!

04_Emerald_Cave
Something tells me the intended solution involves sending one climber over the exit area to build the bridge from the other side. That way, you can solve the level with 10 skills, which perfectly meets the talisman condition. And it's much more interesting than just building non-stop!

09_The_Strange_Relics_of_Lemnos
Simple skill set, yet the level has a very clever solution.

11_Minimal_Design
Possibly the hardest talisman in the Calm rank

12_Ancient_Crash_Site
It's very clear where to use all three bashers, and having only one miner to deal with multiple gem obstacles narrows down the solution. It took me several attempts to perfectly execute the builder-miner combo.

14_Pagoda_St
A great level where you have to be creative with diggers and miners to compensate for the lack of bashers. I think I might have bypassed the second half of the level by building over the second pagoda structure though!

15_Standard_Test_Chamber
This level reminds me of playing Portal for the first time.   The companion cubes, the buttons, the guide lines showing which object is connected to which button. It's all there!(well except for the portals themselves )

19_Iron_Industry
Probably my favorite level of this batch. I love the logic behind it, figuring out the sequence for collecting pick-up skills and how many lemmings to dispatch for them. Not to mention, the level layout looks fantastic.

https://youtu.be/lhHfWl9ZTnI?si=4iDggUQzGkV9T7jR

by shimmier hanging under the bridge

First, the two workers must meet on the lower floor and build a bridge together. After that, one of them should go back upstairs to complete his own task.

Digging through the splat zone to allow the top lemming to fall safely is actually necessary. However, the lemming who digs through the thin floor must not end up on the bottom level, which means you have to prevent him from falling by assigning a builder. But how does he survive the fall after he finishes building? That's where the bridge that the two workers build together comes into play.

Unfortunately your solution is a backroute. You're right that I'm trying to force the player to use both exits though. It's required by the rule! 

Lems Are Playing Freeze Tag – I hoped this level would help you get used to the slider mechanic for the upcoming more difficult slider level.(Watch your step... )

Lighter Than a Snowflake – Looking back now this level might be a bit too difficult for where it is placed. I've received similar feedback from several people.

23:58:30 12/24 – The idea behind this level was: can you make a level with a single hatch and n exits, with a time limit that only allows a solution if you go for all n exits? The answer turned out to be a relatively easy "yes".

Lost and Found – I wanted to give some spotlight to one of the least-used skills: the stoner. You can create terrain mid-air without any starting point for constructive skills and that's a unique feature of the stoner!

Claustrophobia 2 – A spiritual successor to my level Claustrophobia from the previous Xmas pack. The urgency created by the tight timer is completely intentional!

Happy New Year! – Just for your information, several levels were co-authored. The general rule is: the first author listed creates the terrain/objects and the second author creates the solution.

Living in a Fairy Tale – This is my favorite tileset.

The Bear Necessities – Not exactly intended, but your solution is actually better than my original one!

Walking Bearfoot in the Snow – Yes, I didn't want to add too many extra elements beyond the main idea of the sacrificial jumper.

Sky Shield – I think you could have solved this level even without the hints!

Watch Your Step! – The theme I had in mind was that all skills must be provided as pickups similar to rule #3 in the current level design contest.

Warm Cozy Basement – I'm glad you liked this one. It's my personal favorite level in the pack!

Constructus Interruptus – Yes, this level stands out a bit in terms of difficulty. I could have removed some tricks to make it easier but ultimately I ended up liking them too much and kept everything as-is.

Where Angels Dare – Yes, this one is more of a visual level. I drew the scenery first and the solution came afterward!

And They Lived Happily Ever After – If this level made you laugh, then it achieved exactly what it was meant to do.   I didn't have any particular reference in mind when choosing the title.