I've had the same experience, with ligatures applying in languages they weren't designed for. It struck me that the font is a strange place to make the decision

I've had the same experience, with ligatures applying in languages they weren't designed for. It struck me that the font is a strange place to make the decision about what character combinations should be combined. Something like emacs' prettify-symbols-mode seems like a better approach: make the decision per-language. Of course, that's not nearly so simple to implement.