"If you complete a treasure panel keeping one of more feathers"??? ...I'm going to assume you meant "If I clear the requirements for a panel which I have already used a feather on". The answer is no. However, using the feather leaves an icon on the "board" in that space, to tell you that you haven't actually cleared it, which gets removed when you do clear it. You don't get the feather back, though.
Socran's Razor: "Never attribute to massive stupidity by someone else, what could be explained by a tiny bit of stupidity on your own part."
I'm purposefully keeping my feathers. I only need about 49 more panels gone to complete all 3 boards. The bad part is, all of those are difficult lol.
My cousin on the other hand was bragging a few days ago about having used all his feathers. He randomly chose which to use it on. So now he's completely stuck with all the hard panels left, and no feathers(which looks ugly imo).
3ds FC: 0817-3909-5696. PSN Grindpantera. If you add me, please send a PM with your code.