Seeing
Adelheid or
Engel would make me giggle a bit. They're both Dutch words. Actually seeing
Engel on a boy would crack me up...
Jonas is the only one I'd like out of the boys. Having said that, I have to add, that even though
Jonas is the Dutch name for the Biblical character, and most people will be familiar with the name, to see it used on an actual child may raise some eyebrows.