He contacted me.
I think it’s there are no problems in both of the plugins. But probably our plugins have some naming collisions (like if names for some C++ classes are the same - something like Quest.cpp in both of the projects can cause that), which cause such errors. I don’t have another plugin to check it, but if it really is the reason, then to fix it, you need to rename classes in one of the plugins and re-compile it. But it’s better to look at the log file of your project first (YourProjectFolder/Saved/Logs)