Something slurped up the french USE flag descriptions instead of the english USE flag descriptions from sys-boot/refind/metadata.xml when it autogenerated /usr/portage/profiles/use.local.desc I found out when I tried to track down a unicode related crash in app-portage/flaggie.
The French descriptions are also on master rsync, so CC-ing infra-bugs@ to copy the patch once it's in Portage.
Hmm, it also affects pkgcore and therefore gentoo-mirror.
egencache uses parse_metadata_use() from portage.xml.metadata, and from looking at it (in sys-apps/portage-2.3.1), it seems that if the same use flag appears in different <use> tags (even with different "lang" attribute), only the last one in the metadata.xml will appear in the dict returned by parse_metadata_use(). I tested that for sys-boot/refind reordering the English and French <use> flags in metadata.xml fixes the descriptions in use.local.desc.
Patch posted for review: https://archives.gentoo.org/gentoo-portage-dev/message/fb54fe1e82de885368c62abce674502a https://github.com/gentoo/portage/pull/67
This is in the master branch: https://gitweb.gentoo.org/proj/portage.git/commit/?id=db0dddfda68fbeed2dc6c48d9f8168fc2b42b8da
Fixed in portage-2.3.3.