Here's a solution from the Witcher forums.
By "mwnn":
Are you using the offline GoG installers? i.e. patch_witcher3_1.10-1.21.0_2.0.0.44.exe
There's meant to be an issue with the GoG offline installers containing some files which are no longer needed and aren't found in GALAXY or STEAM installs; so the bug doesn't happen with those.
The xx.w3strings files seem to be the cause of the general skills names/descriptions being scrambled - there's one for each language.
There's a newer copy of those files in \patch1.
Try removing [this file] from the PATCH0 folder:
\content\patch0\en.w3strings
(...)
Should fix the issue.
Works for your problem as well.
If you play in any other language and experience these kind of problems remove the respective file (pl.w3strings, de.w3strings etc. from the patch0 folder)
It seems that there is something wrong with the GOG offline installer.
Dear GOG Team! If it's true then please fix the patch 1.21 offline installer.