Ys IX: Monstrum Nox (1351630)

Compatibility Report

• Name of the game with compatibility issues: Ys IX: Monstrum Nox
• Steam AppID of the game: 1351630

System Information

• GPU: AMD Radeon RX 5700 XT
• Driver/LLVM version: LLVM 12.0.0, Mesa 21.1.3
• Kernel version: 5.12.14.arch1-1
• Link to full system information report as Gist: https://gist.github.com/daigennki/fda24d209214da905e9d4b5d6dd843d9
• Proton version: 6.3-5

I confirm:

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

Symptoms

Game crashes after about 12 minutes, and because there are some cutscenes longer than that with no saving allowed, it's unplayable unless the cutscenes are skipped. Sometimes there is some stuttering as well. Graphics settings appears to not make much of a difference for either issue.
Lipsync also doesn't work, but it's the same issue as Ys VIII and can be fixed with the command protontricks 1351630 xact.
A DualSense controller also does not work with the game.
All of the above issues except for the lipsync issue and DualSense issue are also present in Proton-6.12-GE-1.

Reproduction

Launch the game with Proton 6.3-5, try to play for 15 minutes or so.

Log file

Log file generated with PROTON_LOG=1 option is attached. It was very large at 1.6 GiB, so it's compressed as a 22.3 MiB .gz file.
Of particular note is this at the end, though I'm not completely sure if it has anything to do with the crash:

eventfd: Too many open files
Protocol error: process 0150: sendmsg: Bad file descriptor

steam-1351630.log.gz

Start by reproducing the crash with Proton 6.3-5 using the reported 15-minute scenario and review the attached steam-1351630.log.gz, especially the final eventfd and sendmsg errors. Compare the reported behavior with Proton 6.12-GE-1 and verify the crash, stuttering, and controller symptoms separately. Done means the game runs through the affected cutscenes without crashing and the relevant reported issues are resolved or clearly isolated.