[name]Solenne[/name] just feels a bit off to me, especially next to sleek, strong [name]Kai[/name]. Sort of the same with [name]Ronan[/name].
I usually dislike popular names but I just can’t help but adore [name]Zoe[/name]. I’d use it despite the popularity. [name]How[/name] popular is it where you live?
If not [name]Zoe[/name] and [name]Finn[/name], I think [name]Theo[/name] and [name]Eve[/name] from your signature are the next-best matches with [name]Kai[/name].
I actually love [name]Sol[/name]ène. It was the name of the daughter of my host family when I was studying in [name]Paris[/name] several years ago. I would personally spell it with just one ‘n’, as it feels much cleaner that way to me. [name]Ronan[/name] is a very handsome name too, in my opinion.
[name]Zoe[/name] and [name]Finn[/name] do “fit” [name]Kai[/name] very well indeed. The other names you listed feel like a slight switch in style, but that’s not necessarily a bad thing.