Modern systems have started using something called AccountService for properties and operations where the classical NSS falls short. One such property is the user's language.
Normally this property would be read by your display manager and set for the session. ThinLinc however doesn't do that, so the language you configure in e.g. Gnome's control panel doesn't take effect.
AccountService lives on D-Bus and this example shows roughly how to access the current language:
$ dbus-send --print-reply --type=method_call --system \
`dbus-send --print-reply=literal --system \
--dest=org.freedesktop.Accounts /org/freedesktop/Accounts \
org.freedesktop.Accounts.FindUserById int64:\`id -u\`` \
However the machine-parseable version cannot handle the return type (variant), so we most likely need to handle this in C rather than shell script.
Need information about affected dists.