I use the Japanese input method (from the language pack) to solve this. Wish I was joking, but when in hiragana input, you're still able to input words from a R

I use the Japanese input method (from the language pack) to solve this. Wish I was joking, but when in hiragana input, you're still able to input words from a Romanji base, and entire English input in full width characters if you start you word with a capital. As the IME has to compensate for having multiple words from the same keystrokes in Japanese, with Roman characters, you get accented characters in the same menu. I don't exactly see this as a great solution, but with my limited use, it surprises me that this is restricted to a CJK input