Lemmings Plus II is likely going to have far less changes than Lemmings Plus I did. The only levels that might change a bit are Genius 16 and Genius 19, to fix some really major backroutes in them (I know I mostly haven't been doing backroute fixes for these packs, but I think these two are significant enough to warrant it).
Update isn't ready for release yet, but in the meantime I can confirm that (in their unmodified state) all levels are possible on V1.47n. I make no promises yet about the talismans, although all but three of the existing talisman replays at least pass the level (haven't confirmed they actually achieve the talisman challenge yet); with Nice 19, Sneaky 19 and Genius 2 being the three that don't.
Amazingly, only 12 replays broke. Even more amazingly, Genius 19 was not one of them.
I don't plan to reorder any levels in Lemmings Plus II. So, it's just a matter of confirming the talismans are possible, fixing those two levels, and then it'll be ready to go. It's very unlikely that any of the later games will get any reordering or changed (beyond what's needed for compatibility) / replaced levels either, with one exception: I plan to get rid of that awful "Terrible Sky" level in Lemmings Plus Omega, in favor of bringing back "Night Of The Lemming Dead" (since we do still have zombies).