It's not Welsh with that spelling, as far as I know. It doesn't look Welsh to me, and there's not a single instance of it in the births. marriages and deaths for Wales (from 1837-2008). I think it's probably an American variant of Gaenor / Gaynor.
Gaenor is used in Wales - it's always been pretty rare though. ae is pronounced like the i in 'like', so it's GUY-nor.