You’ve already done the work. 
If you look in my “RA-Overlay-Source” repo, there is a “retroarch_template.psd” in it are two layers “Colored Bezel” and “Dark Bezel”. the colored bezel has two color adjustment layers that can be changed to any two matching colors. Just save a PNG of any color you want. (Within reason. Colors with a brightness of more than 50% don’t work very well.) The rest is done by editing the slangp and adjusting the parameters, as you have done.
If you want the exact color of any given RA overlay I have done, the source for each is in the same folder. You can just hide the background layers and save a PNG. 
(Doing this you will also get the frame drop shadow and the bezel inner shadow.)
That’s why I include the source. 
BTW. I think it’s a great idea. I did something similar once just for fun, also using a raindrop on glass Top Layer Image.