I'm currently unable to type any tags in Japanese. I'm using Safari for macOS and iOS and Firefox for macOS, with the official Japanese IME tool. The issue appears to be that the per-character tag matching is preventing the IME from being able to combine two characters into a single character.
Steps to reproduce:
* Select the Japanese Romaji keyboard in macOS.
* Begin typing "nihongo" by typing "ni".
The system is able to combine "n" and "i" into the hiragana character "に"
Dependign on the browser, either the first letter is left as latin and the second becomes a hiragana "i", or the browser unpredictably produces strange series of hiragana. See the attached screenshots.
Looks like this is fixed now!