Zope (2) wraps a proxy around objects retured from an External Method (or behaves in a similar way) that protects member access from other python scripts.
This is exactly not what I’m after. Apparently this is fixable by adding
__allow_access_to_unprotected_subobjects__ = 1
to the class definition. It’s irritating to have to modify external methods in order to make them Zope-ready; at least the fix is (apparently) a one-liner.