When I launch application via keyboard shortcut (System Settings -> Keyboard -> Shortcuts -> Launchers) it does not inherit locale settings as application launched from menu or via ALT+F2 launcher.
For example:
On gnome-terminal launched via shortcut I have:

[aflinta@0708NOT01371 ~]$ set |grep LC_
    for i in $(LC_ALL=C $prog --help);
    for i in $(LC_ALL=C $prog --usage);
    local LC_CTYPE=C;
            __grubcomp "$(LC_ALL=C $prog --help |                         awk -F ":" '/available formats/ { print $2 }' |                         sed 's/, / /g')";
            __grubcomp "$(LC_ALL=C $prog --help |                         awk -F "[()]" '/--target=/ { print $2 }' |                         sed 's/|/ /g')";

But on gnome-terminal launched via ALT+F2 I have the following output:


[aflinta@0708NOT01371 ~]$ set |grep LC_
LC_MEASUREMENT=pl_PL.utf8
LC_MONETARY=pl_PL.utf8
LC_NUMERIC=pl_PL.utf8
LC_TIME=pl_PL.utf8
    for i in $(LC_ALL=C $prog --help);
    for i in $(LC_ALL=C $prog --usage);
    local LC_CTYPE=C;
            __grubcomp "$(LC_ALL=C $prog --help |                         awk -F ":" '/available formats/ { print $2 }' |                         sed 's/, / /g')";
            __grubcomp "$(LC_ALL=C $prog --help |                         awk -F "[()]" '/--target=/ { print $2 }' |                         sed 's/|/ /g')";

All locale setting were set via System Settings -> Region and Language.