"Feel free to come back another time."
Not sure about "zurückkommen". It doesn't sound quite natural to me. I'd say "Du kannst gerne ein anderes Mal wiederkommen".
Is this translation accurate? It seems like the German sentence might be more along the lines of "Be glad to come back another time."
It's ok. I don't really like it but it's fine. The 'gerne' does more refer to the speaker than to the addressee. So, the conveyed meaning is something like 'I'll be glad when you come back'. (You can't infer this directly from the sentence)