Font queries

What do I want to do?

In the context of a pipeline I want to test a font against an known orthography version to know if it will support the orthography.

To that end here is a start:

Another interesting site is: It provides information from the metadata. Is list the languages it supports. But I wonder, what does "language support" or "supported languages" mean in these contexts? Where do the list of languages come from? Where are these languages' requirements cataloged?