I am now running into this same problem. Cannot convert from Goo to Model - Grasshopper / Karamba3D - McNeel Forum
The issue the third part library karamba has types which exist in their .gha and I want to be able to use these types so that my components will play nicely with theirs.
I have yet to find an elegant solution. The only thing I can think is Karamba defining these types in a separate project/dll that can be referenced by other parties. Seems like a bit of an exercise… ideally loading based on dependencies seems cleaner.