I seem to have some audio de-sync during cutscenes on 1.4.0 with this mod (I had not played enough on earlier patches to notice). Neither the video nor the audio seem to be faster or slower so the only option is that they used a "n. of frames" delay to start certain sounds in a cutscene, and the longer it is, the more de-synced new sounds will play. Shorter cutscenes are mostly fine, and also some are fine even with this patch.
Likely unrelated glitches:
-crash in the Lab while exploring the collected ghosts, when going to the rare ghosts section, which was empty for me (can reproduce 100%)
-The piano in the piano boss had some rendering issues for a few seconds
-Camera transition between rooms on the music floor can snap
-Issues with physics pushing you as you are sucking larger objects
The rest of the game seemed absolutely fine, though the frame rate was very uneven, one second 20 one second 50, even with the highest overclock in portable mode, but I've been extra careful into spotting sped-up things or timing bugs, and I had seen none, the game scales to 60 "perfectly" (except cutscenes).