I quite like
Mariangela. It hints at Italian heritage, but I once knew a
Mariangela who was neither Italian nor Catholic, so I wouldn't automatically assume that, not that those are negative associations. It is a bit weighty, but it lends itself easily to several different nicknames, so I wouldn't call it unwieldy. It would sound quite nice with something a bit shorter and less conspicuous. I like quite a few of your combinations, including:
Mariangela Agnès
Mariangela BlytheMariangela Cécile (This is lovely.)
Mariangela EveMariangela IrisMariangela OdileMariangela OpalMariangela PearlMariangela SophieMariangela SylvieMariangela Violet