The ebuilds use "ven" as a possible LINGUAS value, which is neither a valid language tag nor is it listed in linguas.desc. The upstream package doesn't even give a clue what language this is, as its po/ven/ directory is essentially empty.
Thanks, turns out there was quite a few bogus LINGUAS options. Fixed in git. https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=1809366968388aa0e31c8fd0b107743f46731bd2 https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=59c397fcf759528be3a40c58492627f22204ecff