Exilda is a very unusual and interesting name considering it’s predominantly used in the French Canadian community id imagine it was originally a variation of an older Germanic name and used in old French there were lots of similar feminine names ending in ilda in the germanic languages and old French was greatly influenced by
German the franks themselves after all coming from what is now Germany originally. I think the ild part of Exilda must have been
Hild originally the same as in other Germanic names like
Gunhilda and mathilda and Romhilda now both usually anglicised to
Matilda and
Romilda respectively I’d imagine Exilda went though the same sort of evolution. So yes to sum it up the way it’s spelt and sounds I’d look for an origin in old French and the Teutonic or Germanic language group for an original origin.