It would be more typical to say "I wish I could turn back time", if you still regret that presently. If you mean, you regretted before but now you don't: "I wished I could have turned back time" would be clearer than what you have written.

Your sentence is completely OK. It is set in the past, though. In it, you express regret ( in the present) about a past time when you were unable to turn back time even further. A more typical expression of regret set in the present would be: "iI wish I could turn back time." https://youtu.be/GgD9FyE60hs "Could have" is normally followed by a verb's past participle - as you used with "turned".