First of all, welcome (back) to the forum!

As I already commented under the video: The levels overall look very nice and there are quite a few neat little puzzles in there. The biggest point in terms of criticism I would say is that some are a bit too builder heavy or too repetitive, but that's something a lot of people made when they began creating levels, so you are not alone there.

I especially liked the Switzerlem level.
I am eager to see more the future!

If you ever need some inspiration I would suggest looking through some other user created packs.

We are also currently in the submission phase for the 20th level design contest:
https://www.lemmingsforums.net/index.php?topic=4731.0I recommend giving it a shot!