Since porting to EAPI-6, we can't pass parameters to gnome2_src_install anymore, e.g to workaround some Makefile install phase issues via override variables. So we should either make it possible (and revbump the EAPI-6 consumers that actually pass variables to it where it's important - so users actually get a fixing rebuild), or rework all EAPI-6 consumers that do pass parameters from old times, to work without it (e.g adding --with-* options for configurability to configure.ac/Makefile.am) Some other phases might be affected too, but gnome2_src_install is actually getting arguments passed in some places.
Imho we should just revert using default here and copy missing bits from EAPI=6 default implementation as this was an error while updating the eclass to not account for this use. Or we can probably patch to ebuild to workaround that limitation. Not sure why default phases do not take arguments anyway.