For the second -- FFXIV works flawlessly _once you get it set up_, but there's a couple tweaks to deal with to get there -- the launcher in particular (the default/"modern" launcher doesn't play nice). Games with separate launchers in general seem to have more issues/be more finicky in Proton. I don't personally use ACT, so I don't know if there's any real issues with setting it up, but I know others on Linux who do so it's at least possible. For your reshade concerns, GShade[1] comes with a linux install script that I've had no issues with.
[1]: https://gposers.com/