I would imagine that a fileset to some extent can be treated as a compile unit. In that regard, it doesn't make sense to have more than one library associated with the fileset. It would be helpful to have the VHDLLibraries of the fileset return its own library plus the libraries of its children's filesets. This will provide an easy method to get all the libraries of the design.
What is the idea behind `GetorCreateVHDLLibrary? https://github.com/edaa-org/pyEDAA.ProjectModel/blob/38aa30fa778c04e3949ac9599047906628c20d35/pyEDAA/ProjectModel/__init__.py#L837
I would imagine that a fileset to some extent can be treated as a compile unit. In that regard, it doesn't make sense to have more than one library associated with the fileset. It would be helpful to have the VHDLLibraries of the fileset return its own library plus the libraries of its children's filesets. This will provide an easy method to get all the libraries of the design.