Proton: Might & Magic: Clash of Heroes (61700) doesn't start

[veikk0]

Compatibility Report

• Name of the game with compatibility issues:Might & Magic: Clash of Heroes
• Steam AppID of the game: 61700

System Information

• GPU: Radeon RX 470 4GB
• Driver/LLVM version: 4.5 (Compatibility Profile) Mesa 18.3.0-devel - padoka PPA, DRM 3.23.0, LLVM 8.0.0
• Kernel version: 4.15.0-34-generic
• Link to full system information report: https://gist.github.com/veikk0/d0ebb1ddda8f9582d1799df343bfefe5
• Proton version: 3.7-6 Beta

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

Symptoms

The game doesn't start when the Play button is pressed. Steam shows the game's status as "running" only for a few moments.
No log is generated in the home directory despite logging being turned on in the user_settings.py file.
EDIT: I switched to 3.7-6 non-beta and now a log was created for some reason.
steam-61700.log

Reproduction

Attempt to launch the game.

Other

This seems to be a known bug in Wine.

[veikk0]

The game still doesn't launch, but some progress has been made. The cause has been identified as bug 10506, ie. lack of crypt32 DSS provider. The game checks the SHA1 hash on its data files and just exits when the check fails. Wine developer Paul Gofman created a partial workaround patch and apparently the game works perfectly with the patch applied and additionally requires the use of the d3dcompiler_47 override ("winetricks d3dcompiler_47"). I haven't tested this myself though.

Would it be possible to include this patch in Proton?