tx config maps incorrect PO file
Some CPython .rst files have underscore and some have dots, and manage_translation.py doesn't handle both scenarios. It keeps the underscore from the Transifex resource slug.
The consequence of the PO file having the incorrect filename is Sphinx not finding the expected file when generating the translated doc, resulting in English instead.
For instance, the resource library--concurrent_futures currently have filename in this repo as library/concurrent_futures.po, but should be library/concurrent.futures.po. See https://docs.python.org/uk/3/library/collections.abc.html
See example of .tx/config in Polish team or Brazilian Portuguese team .
One way out is to build POT files and use sphinx-intl to generate .tx/config. I chose this in pt_BR, but I would be very interested in seeing a fix in your script.