I can't help you with pronunciation, but I can tell you that according to La cote des prenoms
by Besnard & Desplanques, Maëlys (in that spelling, with one "l") is becoming generally popular in France
these days. Between 1000 and 2000 girls were given this name in 2003.
The only other of the names you list that is included in that book is Rozenn
, and it was rare, being given to only between 30 and 60 girls in the entire country in 2003. None of the other names above are listed in Besnard & Desplanques' book at all, so they must be exceedingly uncommon in France