It's an honor! I clearly remember the day I got the first upwarp in the practice room, it was pretty surreal to have discovered something huge. I looked at your run and it was well played! I think it can go as low as 56-57.
I'll let you know what I think is RTA viable: it's just about everything. Back in my days I used to practice RTA too and I skipped the entire practice room and fight against drill sergeant by upwarping with the statue, I had a consistent camera/positioning setup to make it into loading around 75-80% of the time, charging and turning forward in blind darkness. I'll let you in on a little secret, if you go into first person view and look down you can see the stage below and use that as a reference for your setups.
There is also an input glitch you can use to move during the test boxes at the beginning of the tutorial platforming course, I believe you hold triangle or start and it'll let you move.
The Snuff oob kill is pretty easy, I remember there was a consistent setup in how you walk through the room and approach the corner so that Snuff gives you a guaranteed upwarp. Doing the elevator requires skillful movement. Also do not trash talk the the tank controls, everybody does this and it hurts your potential. You have to look at it as a methodical style of movement that requires precisely timed turning, charging, and sidestepping in alternation. I could precisely skirt along the edge with the perfect angle and get elevator easily every time.
I had a good laugh in that one room during the 2nd dungeon with two monsters and you're supposed to upwarp but it just never does. I remember that room perfectly well, I had devised a movement setup for this as well just like Snuff so the mob always come at the perfect angle to get a consistent upwarp. In fact most of the rooms in the game where you have to upwarp you should always be thinking about your movement prior to lead the monsters in at the best angle.
Where I always got destroyed is well the final dungeon. The arrow shooting section and unending rooms with difficult upwarps and annoying enemies ended all my runs. I like your idea of changing the route early in Snuff to grab the key to skip a room later, that's a good idea. All the key types in this game are reused across dungeons so we should definitely consider every option. In the training room in the beginning which I skip, you can actually get infinite cherry keys I believe, but you had to skip a section with some insane wall platforming. There are a couple more rooms in Snuff that I'm able to easily skip by upwarp, I believe you could save a green apple key it was. Also in the first dungeon the cannonball room, I can't remember what it was but the cycles are always the same and IIRC there's a consistent input timing trick you can do to make it go perfect every time, just like the flames at the start of Snuff.
I recommend continuing to run the game if you like it. It's a rewarding run for sure, there are a lot of tiny details to optimize and I'm certain new glitches waiting to be found. A couple years after all these finds I went into it and randomly I was playing around in the first world.. you know the entrance to the first dungeon, there is a dark mountain/island area with a lighthouse you gotta enter. I was bumping into the scenery and found a way to upwarp on top of the lighthouse by just running in side of it. I wouldn't be surprised if we were only still scratching the tip of the iceberg, potentially there are mindblowingly precise damage boost angle that let you clip into perfectly flat walls or upwarp with small enemies.
