That's just regular keyboard for CJK languages. "today" -> "2025/08/15 Fri", "cry" -> ":crying_face:", etc. It's just small extension to regular "keycodes to full UTF-8 gibberish" process that input method editors handle.

There's nothing wrong if someone make ones for en, fr, de, in my opinion. Correction-plus-conversations like "hors douvray" to "hors-d'œuvre" in one key is going go be useful.