Well, with the last one having that blatant backroute, it didn't take that much time to solve your 4 levels: first one is trivial (well, I think I went the easy way and released a blocker), second one not too difficult either after finding the main idea, only the third one took some time to figure. Overall perhaps like 20 minutes.
I played the new version of level 22 and solved it. Check your inbox, I'll send a PM with my solution soon.
btw, did somebody try my crystal level 'Illusive Paths'? The basic idea behind it is ridiculously simple, yet somewhat obscure and subtle.