

There are issues that severely affect cutscenes, but it's a falcom game from the 2000's so you're not missing much as there's few of them.
The whole game framebuffer keeps constantly flickering if you launch it directly instead of using the Controller Layout Tool to launch it instead. (classified as "minor artifacts" since it can be easily fixed)
Only the very first video plays, which is the intro after starting the game... it's also in slowmotion causing the audio to quickly desync and cut off at around the video's mid-point. Any other video just refuses to play and shows something similar to a display calibration screen animation instead.
Game is perfectly playable from start to finish as long as you launch it through the Controller Layout Tool and don't care too much about the two or three FMV cutscenes.
Finished game with some annoyances
Constant flickering shadows. Several missing cutscenes (test pattern) near the end of the game
Need to start via the launcher every time, otherwise the entire screen flickers
PROTON_USE_WINED3D11=1 %command%
Use PROTON_USE_WINED3D11 to prevent screen flickering.
Completed whole game on Linux, didn't encountered any issues.
1280x800, "Beautiful" preset, WINDOWed mode, Movies OFF. Launch from the config tool, or backbuffer effects will be bugged when not capped to 30FPS.
Backbuffer effects, when enabled and not in Windowed mode, will cause flickering if not capped to 30 FPS.
Full screen flicker with backbuffer effects on.
Limiting framerate to 30 or disabling backbuffer effects will also fix flicker.
Works very well if launcher workaround is used.
If you start it directly, screen is flickering. If you start it via the launcher, everything works fine.

Proton-6.8-GE-1 GloriousEggroll
The game screen flickers, if you start it directly, but, somehow, doesn't flicker, when you start the game via the configuration tool.
The videos don't play while using vanilla Proton. Using Proton GE kind of solves this problem. "Kind of", because as it was mentioned by one of the previous reviewers, the video stream is slower than the audio stream. You can still watch the videos, just not the way they were intended to play.

6.1-GE-2 GloriousEggroll
The game has to be launched through configuration tool and correct resolution chosen. If the game is launched straight, menus flicker. In configuration tool it shows each resolution 4 times for some reason.
With 6.1 videos work, but there seems to be performance issues with videos. When the game plays intro-video, it is very slow and theme song ends halfway the video, because of video being slow.

Crashes before you can do anything useful.
Default version crashes instantly, selecting directx8 at launch takes you into the main menu and everything appears to be working, but as soon as the first cutscene finishes it crashes.

Few minutes playing I did, until moving freely, worked fine after the protontricks item was completed, when using the DirectX 8 version
protontricks 427680 icodecs
and installed only the Indeo 3.2 codec per https://www.protondb.com/app/61500#lDZL6DkbSC
I saw consistent flicker except when I launched the DirectX 8 version
Fullscreen vs windowed could only be selected pre-launch by using the Launch Configuration Tool launch option (in-game options only allow adjusting sound levels)
Worked out of the box
Another user mentioned possibly skipping cutscenes. I haven't played it on Windows, but I don't recall missing anything yet?

video cutscenes don't play, otherwise runs perfectly