I (an English speaker from the US) generally want to see results in English.
Sometimes, though, I'll search a term in another language, and depending on my goals, I'll either want to see results in that language, or results in English that still reference the foreign language phrase.
For example, most recently, I searched "Droit à l'image", the French legal right to one's image, and was hoping to find English-language discussions and explanations of the French law (which do exist online) but the first many Kagi results were all in French. Which would have been great if I was looking for French results, but I wasn't. I would love to be able to filter for only English results, or only French, or something else.
I was able to work around this by adding a couple of semi-related English words to my query alongside the French phrase but it would be great if it were easier than that.
I would see it as a dropdown, probably under Advanced, in Kagi Search, similar to the current Region selector.