I find the healthiest attitude I can take when doing these projects is to imagine I'm in some weird gameshow and this is one of the challenges. I also enjoy the puzzle or challenge of figuring it out as it tests my color knowledge in a unique way. I may be a bit of a masochist. Aren't we all in some ways?
This project was similar to this one from 2013 in that the paint had been applied a million years ago and there was no way to track down the formula. The wall had been severely dented and the patch was clumsy. After cleaning the wound (cleaning all the excess spackle off the wall) I mixed and matched the autumn tones and golds until I thought it looked as good as possible. Nothing is perfect, of course, but upon seeing these pics again I declare "not too shabby".
If you ever find yourself in a situation like this I find that it's useful to work in some additional areas of interest near the actual patch to draw the eye away. Also, don't let your OCD kick in. One thing I've learned over the years is that people aren't inherently scanning for mistakes. More often than not no one even sees the patch. Learning to step away and see with fresh eyes is an art unto itself. But that's a post for another day.