[ ... ]

So here now in the replace function, md decided to correct the
read errors on /dev/sds. Now the pending sectors are down to 7
on /dev/sds. There were some more errors which were also
corrected, and now the pending count is down to 5. Recovery is
still ongoing. [ ... ]  I expected it to correct the read
errors on the drive then, but it seems it didn't. [ ... ]

That seems to me a big misunderstanding (or delusion).