Valve pushed out an update to Proton Experimental with the following fixes that made the following games playable via Proton.
True Reporter. Mystery of Mistwood
George McGeehan Gamer Hero
Road to Vostok Demo
There were also some notable fixes:
Fixed Bayonetta crashing on certain systems.
Fixed TouHou Makuka Sai ~ Fantastic Danmaku Festival Part I and II crashing during boss fights
Fixed crash in Disaster Report 4: Summer Memories epilogue.
Fixed recent Proton Experimental regressions:
Networking in Ground Branch's community test update works again.
RoBoRumble now launches fine on new prefixes.
Proton Experimental is ever-evolving and there is no set timeline for when these fixes will make it into the next official Proton version, but it's very easy to switch to Proton Experimental in the game properties, compatibility menu if you want to try out these fixes early.
To see a full list of what is in the current version of Proton Experimental, click here