a) Probably not something to fix in released versions any more, so increasing version from 3.5 to 3.8.

b) Regarding shared library unloading and the problems mentioned, I'm also not sure if there is a way to safely unload transitively imported libraries, e.g. if the extension module is a wrapper for an external C library (which then might come with its own dependencies again, which might still be in use by other extension modules, etc.).