The ebuild should probably provide a nls useflag to disable installation of internationalized manpages. Sadly, the program's build-system does not have appropriate toggles to disable the installation. Ebuild patch? Upstream request? Manual removal of the nls files on !nls?
With you on this being also an upstream issue, I mean we can hack it in but I dislike hacking stuff in ebuilds, when it's trivially fixed $upstream. If they're unresponsive, feel free to reopen this bug, then we fix it in the ebuild
typos--, sorry for the bugspam