Did you remove the 2 other font folders in the GIMP's Preferences?
1 folder from the system and 1 folder from your account... GIMP certainly load those 2 as well by default, if so this "FontBase" has no uses because GIMP will fetch those 2 folders if you do not remove them. (copy/paste the path of those folders on a text file, to not struggle getting them back just in case)
On Linux I use Font manager for years, it's a very good one but exclusive for Linux,
On the other hand for Windows I did some search and found FontMatrix > https://github.com/fontmatrix/fontmatrix it's FLOSS did you tried it? You can activate de-activate fonts as seen on their screenshot.
1 folder from the system and 1 folder from your account... GIMP certainly load those 2 as well by default, if so this "FontBase" has no uses because GIMP will fetch those 2 folders if you do not remove them. (copy/paste the path of those folders on a text file, to not struggle getting them back just in case)
On Linux I use Font manager for years, it's a very good one but exclusive for Linux,
On the other hand for Windows I did some search and found FontMatrix > https://github.com/fontmatrix/fontmatrix it's FLOSS did you tried it? You can activate de-activate fonts as seen on their screenshot.
Patrice