Why the final "e" in "puellae" doesn't sound like a Spanish "e" or French "é", German ä?
(I just ask to learn, not saying the pronunciation is not good)
Actually it does, it just depends on where you live (All the countries didn't recreate the latin's prononciation the same way)
I think as well that "ae" should be pronounced like a Scandinavian Æ or German Ä
Now I know that the "ä" is for the Ecclesiastical Latin and the "aye" like in the "y" in "my", is for Classical reconstructed Latin!
Hearing a stress on the final syllable of dormiunt.
Whould "the girls sleep" also work?
Yes; English has 'progressive present' (are sleeping) for actions underway at the moment; but in Latin it will be indistinguishable from the 'timeless present' (sleep): both are dormiunt.