So, for anyone willing to modify their engine code, I dug through the commit of the original fix and found the file/line they changed. Here’s the diff from SRetainerWidget.cpp:
You can see they removed the NoGamma option, and set the render target’s gamma to 2.2. Up to the reader if they want to mess with it, there’s some comments talking about gamma space blending issues (presumably why they reverted the fix) so if this causes problems for y’all revert and use the material approach above instead.