This is something asui-settings could handle. Simplest method would be three input fields where you type in the font family you want. This is something you would need to know about the fonts you uploaded to the device. Would be better if you could tell me how to extract the style and font family from a TTF file so asui-settings could scan /use/share/fonts and /home/user/.fonts and display a drop-down of installed font families for each style.