Last I checked the highest quality widely used translator was deepl.com which is a commercial service that lets you translate only small snippets for free. To do larger ones you can upload them as pdf's, which increases the size limits.

I've been using the local translator built into Firefox and it's better than nothing, but it's pretty rough compared to either google or DeepL.

I don't think Kagi has its own translation service. They resell someone else's.