Yes, it's solvable now (I saved 45% and the new requirement is 43%). I'd suggest lowering it still further, as you want the player to have some margin for error in Tricky.
Similar remarks go for several of these levels, and (especially since I'm playing on a laptop where keyboard controls are not so easy) this is becoming a real playability issue. For example, Tricky 18. Holding the crowd with a single blocker is easy, so all the lose-1 requirement does is enforce fast pausing, which is not an interesting puzzle. And then you have to start again because of the hidden trap; if the save requirement were more lenient this would be less of an issue. (In the original Lemmings that trap only occurs in Rendezvous at the Mountain, which allows you to lose
twenty.)
Tricky 13 is a good puzzle, but I think my solution is unintended. I made a blocker, sent up a climber, made him build two bricks then mine to turn around when he hits steel, then bashed to free the crowd. (I think this is unintended because exactly the same solution solves Tricky 16 and, substituting a miner for the final crowd release, Taxing 1.)
Tricky 14 is an okay "hold-the-crowd-without-blockers" level. Tricky 15 is nasty -- the fireblower is positioned so it looks like it will kill the lemmings, but it doesn't. Sure, it's easy to guess since the limited skills make the route apparent, but it's still not exactly treating the player fairly. Then Tricky 17 -- I won't complain about the traps; it's easy to guess they are there when the level would be trivial without them; but with such limited skills to get past them, this is much too hard for Tricky.
I've had a look through the rest of the set, and I have to echo namida's criticism -- too many hidden traps and levels that are just building. But not bad at all for your first levelset, so don't be disheartened