The number would be most of the people who use the keyboard shortcuts && who use 2 or more layouts && who don't want to change languages to search for something.

It's just muscle memory for me.

CTRL+T -> x <search_term> -> ENTER

Most often I enter <search_term> with CTRL+V, so the sequence is:

CTRL+T -> x CTRL+V -> ENTER

Nowhere in that sequence is the keyboard layout important (if you don't write anything, but just paste).

Just like CTRL+T works even if you're not writing in a layout where the "T" key is mapped to the letter "T", so should "x" work no matter what it's mapped to.

At least 2.

Being able to put language-specific shortcuts on keys that change with the keyboard layout is damn useful.

Why does software have such powerful modes for Python and JavaScript, but never for French or English?

I think everyone who regularly writes eg both Spanish and English, or Chinese and English etc will be affected. That's a LOT of people. Not all languages rely heavily on accents or special symbols but those do. (For example in Spanish you don't want to mix up 'año' and 'ano' :)