I dug out my desktop PC running Manjaro just to try it out. Indeed, the timings surpass anything on the other emulators. Even though Knife Edge still plays too fast, it does appear to slow down to the proper speed when there’s a lot going on. I also tested Body Harvest’s intro cutscene, which does show improvement as well, but it’s still too fast in several parts so the music and sound ultimately still desync.
I then tried OoT’s ending cutscene, which has emerged as yet another test case as of late. Most emulators play the Lon Lon Ranch scene too fast, so the music ends up lagging horribly behind by the time we see the sages up in Death Mountain. Ares actually has the opposite problem now: it ends up playing it a bit too slow. While the real hardware slowed down in several parts of the cutscene, ares slows down more than is necessary in those parts, leading to the music being ahead in several points (a good place to check is when Malon appears: she needs to start singing the moment she appears on screen). though it seems to almost even out by the end somehow. That said, the fact that slowdown actually happens tells me they’re on the right track.