In the tcsh-6.09 RPM, the greek translation is put in
while the correct is
All other translations are located in /usr/share/locale/el/
The two-letter language codes come from ISO 639-1:
The "Greek" language is depicted with "el".
I think that at some point of time, the entry for the Greek language
in libc was incorrectly "gr" and it has been corrected (somewhere in '96 or '97).
Ditto for tcsh-6.10-1.
Fixed in tcsh-6.10-2. Thanks for noticing.