UngeheuerLich
Legend
I would be ok, if they regen while they are bloodied and shape shifted.This is also a chance to insert monster intelligence and planning into the mix. Its fair that if its just random wearwolf X and the party comes in knowing about wearwolves, they can use their silver or magic weapons and its done.
But...perhaps the wearwolf is a noble that weapons have to be checked and bound in the armory before going into their home? Or perhaps the wearwolf has planted superstitious that silver is poisonous to people and so people in an area dont' allow silvered weapons or anything of the kind.
There are opportunities to craft an encounter beyond the statblock that can be much greater than what the stat might otherwise indicate.
Which is a good segway to regeneration. Regeneration honestly in terms of a fight rarely matters (partly is because its just too damn low for most monsters). Getting 5-10 hp a round back just doesn't change much.
BUT....where regen shines is outside the encounter. Ok your wearwolf escapes....and suddenly a couple of minutes later the party is now dealing with a freshly healed wearwolf ready to go again, while they are still beat up. That kind of threat is what makes fighting those kinds of creatures particularly scary, you cannot let them live, because otherwise all the work you did to defeat them was for naught.
I don't like most monsters that just undo everything you did.