Understand that this is not an edit of ReShade itself but shader code.
"reconstructed HDR via inverted tone mapping" well, we've been doing that for ages, 1/1-x is simplest way to amplify bright pixels and get HDR of some sort. For my preset in Skyrim SE I inverted the tonemapping and color operators as well (if possible, some code is not bijective).
What game does: HDR data -> tonemapper-> LDR data.
As he knows what exact tonemapper the game uses, he can do this:
LDR data -> inverse tone mapping function-> HDR data. Entirely shadercode. Almost all tone mapping functions can be inversed.
I just wonder why SonicEther didn't take notice of ReShade yet. I'd welcome the idea to have him on the team of contributors, he has quite some talent.
Yes, it always has been. It's just hard to tweak because often the tonemapping parameters are not known and false guesses could lead to extreme results. Elite Dangerous is a good game for that because the space scenes are mostly dark with some small bright patches, every bloom will look good on it.
About the current bloom, idk. It's a very old SweetFX code and no one of us really bothered to write a good one that's release ready.