This note from Stable Update 2023-10-09 might have some relevance:
Using this procedure again looks like it should manually overwrite while updating the glibc-locales package; maybe this will help; maybe not.
sudo pacman -Syu glibc-locales --overwrite /usr/lib/locale/\*/\*
Please also note that potential help is given by volunteers (mainly) who do not necessarily live in compatible locales; and may (or may not) have any useful responses to offer.
A little patience (and humility) is often appreciated.
Cheers.