At first glance the current behaviour is correct:
1) Bundles aren't shared libraries, but plugin code. It should be
possible to load bundles, but I don't agree that find_library should try
to locate them, specially given this bit in the documentation:
[quote]
The purpose of the find_library function is to locate a library in a way
similar to what the compiler does (on platforms with several versions of
a shared library the most recent should be loaded), while the ctypes
library loaders act like when a program is run, and call the runtime
loader directly.
[/quote]
2) There is no prescribed suffix for bundles. Python uses .so and some
other packages use .bundle, but that's just a convention that a specific
software product chooses.