Diva 06, "Diggas in Paris": I remember this trick from your L2 Let's Play, where you repeatedly assigned and cancelled Stompers (which are basically synonymous with Diggers) to move horizontally. But that almost would have deprived you of a way to remove the last bits of the Eiffel Tower, forcing you to spend Builders on that. Pretty clever!
Diva 07, "Born this way": I think you mainly just swapped the use of a Stacker and a Builder here, in comparison to the intended solution.
Also, I noticed that the labels for the pre-assigned-skills on the hatch overlap in New Formats, so I might have to bring back the old style of labelling the hatch with pickup skills, so that the order in which Climbers, Swimmers, Floaters, and Gliders appear becomes apparent again.
Diva 09, "I won't hold you back": You cleverly used the Glider to give the Fencer a head-start in front of the crowd. In the intended solution, you can't prevent the second Lemming released from the hatch from turning around in the Fencer tunnel; that lemming then becomes the Glider instead, bouncing off the dart arrow to land on the lower platform, and then he completes the path from the other side. But since both solutions require all the skills, both are fine!
Diva 13, "Brick house": Totally not intended, but that was pretty darn clever! Especially the tiny piece of terrain you left over on the left side, so that the Climbers don't splat from falling straight into a Digger tunnel. I could prevent this by adding steel to the bottom layer, but I found this pretty amusing.
Diva 14, "Foot of the mountain": I never expected anyone to use the left side of the level - the intended solution basically just creates one long Fencer tunnel. But directing the lemmings back and forth from one side to the other looks very elegant, as well, especially with the way you used the (cancelled) Fencer for crowd control instead.
Diva 15, "If you're going to San Francisco": When I saw the beginning of this solution, I thought it would be another backroute; but you still ended up using all the skills, and there was just as much timing involved as in the intended solution, if not even more. Getting on top of the bridge through the lower part on the left was definitely efficient, but then you needed more skills towards the end. Very clever alternative solution!
Diva 16, "Puff, the Magic Dragon": Ah, yeah, that lightning trap from the ONML Bubble tileset is now joint with the engine that creates it; in Old Formats, it was just a single pixel of a dot that I could hide in the dragon's eye. Now it looks as if he were holding some kind of goblet on top of his head. Is the dragon now guarding the Holy Grail?

Since the trap is somewhat relevant to the solution, I can't simply hide it. And if I make it "no overwrite" again, the lightning would be displayed behind the dragon terrain, I think, rather than on top of it.
Diva 17, "Believe in life after Lemmings": You spared one Builder and one Basher by using timing to isolate the first pioneer; the intended solution re-seals the Basher shaft in the beginning behind the pioneer, with a Builder, which then consequently needs to be cut through with the remaining Basher later on. Apart from that, this is the intended solution.
Diva 19, "Barcelona": That was quite a complex approach, but valid nonetheless!

This level still unintentionally featured the Millas sprites, I'm going to swap those out for the next update. I don't have any issue with them per say, far from it; I just don't think they particularly fit to Spain.
Diva 20, "Only time": This was another radiation-based level in the original, so the intended solution can't really be replicated in New Formats anyway. I upped the save requirement to increase the challenge; in the original version, a bunch of lemmings die, because the radiating zombies free them before splatforms can be built. Without those radiating zombies, the 9/11 reference (which Arty correctly identified during his Old-Formats Let's Play) obviously also gets somewhat lost in New Formats.