I think I am doing everything by the book, adding
{{tts ja_JP voices=Apple_Otoya,Microsoft_Haruka:Field}},
but still keep getting an error claiming sound files are missing. I managed to work my way around it by adding them brute force on the desktop version and save them into the cards, but would much prefer this to work properly.
It looks like you’re asking for Apple and Microsoft voices on an Android device. Have you checked to see what TTS services/voices are actually available for you? Field Replacements - Anki Manual
I tried to use it without specifying the apple and microsoft options, hope it might default to the first available android value, but got the same issue. Apologies, how can I check what is available?