Echoing Larry's insightful summary, it would not be particularly rewarding to pursue a goal of making the whole world of reprs consistent.  But as Antoine and Serhiy began to point out, the multiprocessing module not only has its own Event, Semaphore, BoundedSemaphore, and Barrier, it attempts to directly mirror the threading module's equivalents.  If there's a change to the reprs for these in the threading module, then given the special relationship between multiprocessing and threading, I suggest it is worth the effort to update multiprocessing accordingly.

I have created issue25066 to separately address this proposed change to multiprocessing.

I've gone ahead and provided a patch for issue25066 to reflect the "majority opinion" on the reprs' desired format.  That patch should pass all tests once Serhiy's patch is similarly updated to match what Larry summarized.

If this issue does reach a happy conclusion and Serhiy finds time to update his patch, would someone please also take a moment to review the patch in issue25066?