Hi, there is a few things that could be improved here for much more accurate times, if I was mod temporarily I could fix it up.
the times are already measured to every single frame using very specific starting and finishing points, combined with an outside program measuring them and shortcuts allowing to go a frame back and forth if needed, and also what is the exact framerate
I literally have no idea if one CAN make the timings better, with any additional program
I was going suggest adding a in-game time which cuts out the times of the screen that shows the "next level" options. and there were a few more things
I'm currently moderating a game with over 200 active players so I would be able to help decently lol
in-game timer makes sense if there's a part of the game the player has no control over, like a loading screen but you have full control over when you go to the next level, sure it's always non-zero, but that's just the nature of speedrunning in general