There is a function in Inkscape that refresh font list? Anytime I install a new font I have to restart Inkscape to use it.
Something like "Rescan font list" in GIMP.
Inkscape get all font list when starts. Then problems come when you try to add new fonts if you don't use right permissions (linux OS) , bad locations (Wiondos AppData folders - from install of inkscape software) or something else.
One example: to install the .ttf files use right clik into explorer and use Install from menu.
If you want a script to parse all your fonts then Inkscape let you using scripting languages to create new Inkscape functionality.