Can't say I took it as a deadname, but he did keep trying to correct people before just giving up with his mother. I took it as more of he changed his name (presumably to better fit in in Sharlayan), he now prefers that name, and his mother refuses to respect that. There's no denying Cahciua cares for him (she does show that), she just doesn't respect him, which is probably why their relationship rubs me the wrong way (also the weird decision to have him have a completely different accent, but that's a separate gripe).