as you said the older SRT doesn not work after the game update as said SRT ain't being worked on anymore, there is a SRT Plugin Manager that works for most RE games and a few other games as well developed by a few people in the RE Speedrunning community. https://github.com/SpeedrunTooling/SRTPluginManager

I mean there is a leaderboard for the original version + EMU where this is a thing already so not sure if this is something needed for the remaster. Just my opinion though.

As Nemesis said, the submission video need to have audio but that doesn't mean you have to listen to it. As long as the video do when submitting it you are fine.