you cannot use $ARCH in SRC_URI because that's a cached (pre-evaluated) var, it's not evaluated each emerge (except the USE conditional)
just trying to prune down the ebuild
pastebin the ebuild?
github its far from done , but
SRC_URI=""; for a in amd64 x86; do SRC_URI+=" ${a"
https://github.com/necrose99/necromancy-overlay/blob/master/app-emulation/veil-wine/veil-wine.ebuild
SRC_URI=""; for a in amd64 x86; do SRC_URI+=" ${a}? ( something ); done" perhaps :P
just a set of deps for a wine install ie
'~x86? ( veil_wine_setup_x86 )' should be 'x86? ( veil_wine_setup_x86 )'
https://answers.launchpad.net/ubuntu/+question/8686
setup Sandboxing.....