Vedic Support for Indic Language Fonts

Hello! I am looking for support for several vedic/indic language ligatures that don't exist in all fonts uniformly (or at all, in some cases) for use on Google Sheets.

1. We can specify multiple fonts on Google Sheets to define a default and several backup fonts so we can pull a character from a font that has a certain ligature enumerated. There is no support for this.
2. Alternatively, if we can also create a "franken-font", we could use that as well. Is there a way to do this properly?
3. Moreover, if we need support for a specific ligature that does not exist across all of the fonts, can we request the addition of a new ligature for a specific font?

What's the best way to get around this problem in Google Sheets?