The problem is that most people who would need and benefit of those changes don't have the time or skill to make them themselves. So being able to share and distribute the modified version is an absolute bare minimum for the right to repair.
However, when the organization transfers copies to other organizations or individuals, that is distribution. In particular, providing copies to contractors for use off-site is distribution.
https://www.gnu.org/licenses/gpl-faq.html#InternalDistributi...
So whether the FSF calls something distribution in their own FAQ is irrelevant, unless the FSF is your lawyer and giving you legal advice.
If you send them the software, they reverse engineer it and fix bugs that's not distribution.
If you send it to them, they fix bugs and then start using it themselves that is distribution.
I used to be able to fix a Morris Minor; but I wouldn't dream of trying to fix anything but the bodywork on a modern car.