I am a Bible reader from China, I search from Google to Scripture App Builder, it is really a great book for the artifact, I realized, a Latin Bible, which are all normal, but when I use the miaounicode to realize the Bible, font display is not normal that figure, my test environment is android4.2, the font is miaounicode, using grandroid. I also used the other two fonts tested, font download connection: https://github.com/phjamr/MiaoUnicode/blob/master/MiaoUnicode-Regular.ttf, another font download link: http://scripts.sil.org/cms/scripts/page.php? Item_id=Miao, did not show the character of the tone, I also tried to use crosswalk, also failed, hoping to get help from the organization, thank you.
I think 4.2 could be the problem. So are you building an App? I am not with the organization but I can try to help. Can you share a link to the APK file with me so I can see if it works on my Xiaomi?
You can create a support request at https://software.sil.org/scriptureappbuilder/support/. I would copy your project to Google Drive or Dropbox and share the link in the support request. Someone would likely need to see your content with the font.