The same word is pronounced more like Che low in Italian so anyone who doesn’t realise it’s Spanish rather than Italian will pronounce it wrong, as will most English speakers if they don’t know any Spanish, probably
I don’t hate it but I think it’ll be annoying for him.
I think Kai and Cairo are awful, I’m not a fan of angel, I think Julian is a bit wet personally but I wouldn’t judge it. I’d assume French not Spanish with Claude though I do like it and Casper is quite popular now.
Is there a reason you’re not going with the more ‘classic’ Spanish names like Alejandro, mateo, Lucas, Carlos or cesar, that would all work easily in the uk if that’s the main aim?
if you’re not bothered about it being Spanish some similar vibe names to cielo might be enzo, Leo, Elias, rafe, Jovan