Indeed manual replacement is a possible fix, it would behave the same as manual code changes, but will be erased if you use the mod system to add or remove mods. You should be able to copy the contents of the file "...\Es-02-ChastityBelt\scripts\person.gd" directly into your version of the file and add it to the end of the file with a decent text editor (crude editor's like Window's Notepad do not handle newlines correctly). But the larger issue is that such problems tend to not appear alone, and you may find yourself fixing many files.
Just to be sure, the mod system does not report any problems with applying the mods? It should be fairly sensitive to most issues, though the bugfix mod improves that a bit. It should report a lot of unused files, but the new actions folder, ChastityEvents.gd, and ChastityBeltMod.gd can be ignored.