> Graecia capta ferum victorem cepit (once defeated, Greece conquered its savage captor)
A better translation would be "captured Greece has conquered its savage captor", since that better captures (pun intended) the intended parallel between capta and cepit--both are forms of the same verb. (Also cepit is perfect tense, hence "has conquered".)
> Also cepit is perfect tense, hence "has conquered".
The Latin perfect is the equivalent of the English perfect. It's also the equivalent of the English simple past; whether "Greece captured her conquerors" or "Greece has captured her conquerors" is the right translation depends on whether Horace was writing about the past or the present (that is, his past or his present), not on the form of the Latin verb.
> It's also the equivalent of the English simple past; whether "Greece captured her conquerors" or "Greece has captured her conquerors" is the right translation depends on whether Horace was writing about the past or the present (that is, his past or his present), not on the form of the Latin verb.
Yes, you're right. I still prefer the "has conquered" translation, though, because I think Horace was talking about a condition that was still there in his present, not just what had happened in his past.
> English is not my mother tongue and I thought "captured" would have sounded a bit too archaic.
I don't think so. "Captor" might be, though, even if "captured" isn't. Another possible translation that doesn't use "captor" would be to swap words around to: "Conquered Greece has captured its savage conqueror". That actually might better match the sense of the original Latin in modern English; the Latin victorem is probably better translated as "conqueror" than "captor".
(Edit: One other more pedantic refinement: "Conquered Greece has captured her savage conqueror." Since the Latin Graecia is feminine, not neuter.)
A better translation would be "captured Greece has conquered its savage captor", since that better captures (pun intended) the intended parallel between capta and cepit--both are forms of the same verb. (Also cepit is perfect tense, hence "has conquered".)