I'm French and it apparently took more than four decades for me to TIL that we have our own Gruyère.

I always assumed we were just calling Emmental the wrong thing. Then again most of what we call Gruyère is a somewhat industrialized store-bought thing that arguably tastes like neither Emmental not Gruyère (but at least it has holes, I guess). And to boot, I'm pretty sure we call "Gruyère" some of the products that are labeled as Emmental anyway.

In retrospect, it makes sense we'd have our "own" given how finicky we are with names (of things we produce).

Edit: turns out we've also bastardized Emmental anyway.