I'm not sure if this will help but try to read this info about the fonts:
https://wiki.esoui.com/Fonts
In there you'll find the fonts and style strings like:
"MEDIUM_FONT" -- or "BOLD_FONT"
"soft-shadow-thin" -- or "soft-shadow-thick", or... see below
see below = the list of the XML and font entries below in the wiki.
If you search the lua files and XML file for these texts you should find them, and be able to replace them with other values from the list.