After looking at the Czerka depot again, I think it may be part of Tatooine, not Sleheyron.
First, its module naming, m21aa, is more consistent with Tatooine, as m19aa is the Rakatan temple, and m20aa is the Sand People enclave. The next highest module number, m22aa, is part of Kashyyyk. The left over models from Sleheyron are named m31aa, m31ab, and m31ad, putting its module naming between Manaan and Korriban (a likely range of m29-m32).
Second, the texturing visible on the outside doorway is more Tatooine-ish, not like the Sleheyron screenshots. The depot may have been where the player was to attack when leading the Sand People against Czerka.