[CE] Need Detailed Explanation of How Font Symbol Favorites Function

We are trying to use the file MstnFontConfig.xml to standardize on a specific set of fonts. We also would like to setup standard favorite symbols for many of these fonts. I have tried modifying particular fonts  in that file to add some special characters thinking they would then appear as favorites. Apparently, that's not how it works.

And manually adding favorites seems to use the font that was used when creating the favorite as opposed to the active font. In some instances, users can mix fonts, but in other cases, we need the font to remain consistent throughout the text element and would like favorites that are tied to the font they represent.

Is this possible and if so how?

And how does one setup shared symbol favorites?

TIA