In-game typefaces are overridden by system ones on some Android devices

I’ve noticed that on some Android devices system fonts override custom fonts I provide with my game. My font files are placed in the game’s root directory, all are in the TrueType format, the game called them as “fontname.ttf”, all file names are in small caps (but have hyphens, like fontname-bold.ttf). All works fine in most cases, especially on iOS and Windows, but on some Android devices my fonts are overridden by system ones. Sometimes that is pity, because users may use something like Comic Sans or something:) So it changes the game’s visual appearance and even ruins some GUI-elements. Is there a way to prevent the overriding?

P.S. It looks like some users may use special font managers to use their custom fonts in other apps.