Really a very good tool, thank you for that! You create so many useful things, it's great to watch you in the development.
Now to my suggestion:
It would be good if the standard output language in Translate could be saved. It is a bit cumbersome to have to select your own language again in the drop-down menu every time.
(Certainly interesting for later development steps) For students/language learners, a dictionary with spaced repetition mode (something like Anki) would be great, so that newly learned words can be saved directly and reviewed later. In combination with an AI model that allows conversation in foreign languages, language learning could definitely be taken to a new level.
A (browser) extension that allows you to send selected text directly to Kagi Translate or a popup that displays the translated text directly.