Custom font implementation on Android

Hi, I work for a mobile app company which supports 98 languages and I wanted to start a conversation (more ask for advice) about font implementation on Android.

I understand that this is a tricky area when a font does not have the language support necessary and must then rely on a fall back system font. The problem really arises when characters in the same word can take form i noticeably different font styles or weights.

I was wondering if anyone has tried to implement a custom font on an app which must support more ‘obscure’ language characters, and how they over came the above issues.
Has anyone found a solution to controlling the fall back system font, so that it matches as much as possible to the custom one?

I’d love to hear other peoples thoughts or experiences in this matter. Thanks!

I think you better understand how will it work as you already work for an android application development company where you used to support necessary fall back system font and in that case every app is supported.