The descriptions are ultimately done in a loalization file, which cannot be changed in the editor anyway. Statuses like Frozen, Stunned, etc. have the handles to the names and descriptions hardcoded in the .exe, I assume it is the same with talent names and talent descriptions.
One would have to unpack the localization file, which is Data\Localization\English.pak (or German.pak or Russian.pak or whatever). Unpacking this file creates some subdirectories and in them is the language file (English.xml ...), it's a big XML file that contains all localized strings.
I guess that removing English.pak and replacing it by the unpacked structure would be the way to edit descriptions. Then the XML file could be edited. It is very big though (English.xml is bigger than 4MB).
To unpack .pak files, one does not need Larian's editor but Norbyte's unpacker tool, the link to the download is in this thread
EE pak extractor