Issues should be reported at Kactus2 project management site https://kactus2.cs.tut.fi
Otherwise support is provided by email: kactus2@cs.tut.fi
When contributing to Kactus2, you should see the wiki at the project management site. It will guide on essentials like building with Visual Studio and plugin development. Contributions to Kactus2 core, the IP-XACTmodels library, and the plugins provided by TUT will not make to a release unless we accept them and you agree to transfer the copyrights of the changes to TUT.
When creating a plugin, you may keep it closed or open source, and the copyright stays with you.