How difficult would it be to move this motion light around corner?

Simple. Just make sure you cut your hole the correct size so the hole will be completely covered. Also make sure that the hole you cut is in between the studs before you start cutting. Depending which way the wiring is coming to the previous light. You might need a short piece of romex. Then you just have to put a blank cover over the existing hole

First personally, I’d leave that existing light fixture b/c if you move it you’ll have to cover up the hole anyway. Just put a burned out bulb in it. Then get another light fixture of the same type - they’re cheap, and I bet you can tie into the existing light you are not using without having to get into the attic with “jumper” electrical wire that you fish in the attic from the old light to the new light. They are only several feet apart so that should be easy.

You’ll have to drop the existing light to tie in in the electrical junction box but there should room to do it. You would just fish a wire to the new fixture and new electrical junction box that needs to be installed to connect the light fixture to.

This may sound like Greek if you know nothing about wiring, but if you have a friend with a little knowledge of wiring, and you watch several YouTube videos on installing outdoor flood lights I bet you could do this with getting into the attic (but you might) and hiring a electrician.

Just pull the two panels down, drill a 3/4" hole thru thru corner rafter. Run a jumper wire from the old fixture and install a new light fixture.