Most things are not generalized. So Codetools, but also the project system that assumes a compiler that can find its own files.
Lazarus is simply not setup as multilanguage IDE/RAD
And then the Lazarus IDE is GPL, which prohibits closed source usage. Afaik an exception to that are the plugins, if you talk to the IDE via the plugins that is exempted from the GPL, even if it is a linked together.