Δωρεάν as well?
Yes, and that should already be accepted.
Could τζάμπα also be accepted?
And "αδικαιολόγητος" = gratuitous?
I hadn't heard that word before, but δικαιολογία = justification, so αδικαιολόγητος sounds reasonable for "unjustified" or "gratuitous" in the sense of "gratuitous insult" (which is not "free of charge" but "unjustified").
What about ελεύθερη?