Hmm, I am not wexactly sure what you mean. Are you referring to the autocomplete function? If that isn’t working, I am not sure how to fix it. But as to not being able to type diacritics on an Android phone, this thread outlines some methods to get started: Pali keyboard - #12 by Gillian
I myself use the AnySoftKeyboard together with Ven. Yuttadhammo’s ASK - Pali & Sanskrit Pack, both available via Google Play. I think this is how I got everything ready: Install AnySoftKeyboard first, then the language pack; finally, select the desired Pāli layout via AnySoftKeyboard language settings under “Enable keyboards and languages”).