English names, French accent?

Hello! I'm Sage, and I'm new. I bumped into this comm forever ago and then lost track of it, but now I've found you and am super stoked! \o/

Anyway, I need a little help with names. I realize there are a number of French names used by English people that are pronounced with little difficulty, and so the opposite must be true, too, right?

What I want to know, though, is what sorts of names are considered difficult to pronounce for the French. I have characters for original fiction whose nationality I changed to French forever ago, and still haven't changed their names. I'm wondering which ones in particular especially need name changes.

"Ryan" in particular is sort of a grey zone for me. It seems like it wouldn't be hard to say, given my mid-level understanding of French, but I've never heard of it being used by the French, *and* I'm an anglophone. :/

Basically, what I need is an idea of what sort of sounds are not easy to say for a non-English-speaking French person. What kinds of English names would you simply be unlikely to find in France?

H-help?