Your understanding is correct SuzuTitor as per what Small, Normal, and Wide mean. I meant "even" as in the slider is precisely in the middle of where it can go (which is the untouched, default position); I apologize for any lack of clarity, but it seems as though you did figure out what these terms meant regardless.
Likewise, the tournament went down yesterday, and I was honestly pretty disappointed with my own performance (I sucked, just a major off-day especially early in the day where I just wasn't "feeling it" at all), but as per how customs went... Well, procedurally they didn't cause issues, but people were... non-adventurous. An overwhelming majority of players weren't familiar and responded by just declining to use them at all, just picking defaults. Steeler ran Dragon Rush on Charizard in some of his games (he went back and forth between it and Flare Blitz), I was running 2311 and 2313 on Rosalina depending on match-up (not that I use Guardian Luma ever anyway, gotta figure out the situations that one is useful because it's definitely wrong to pack Gravitational Pull in several MUs), DMX the local DDD player started running Bouncing Gordo and Armored Jet Hammer later in the event once he saw them in action in friendlies (and Bouncing Gordo is seriously really good; IMO in the long run it will be the only thing DDDs use), I think Stealth was using customs on Shulk (I didn't see any of his games but know he strongly prefers Power Vision), and I think that was about it. Most mind-blowing to me was me telling a Little Mac player that custom KO punch had more armor but was otherwise identical and then him picking default anyway despite him never using neutral special other than KO punch anyway (I mean, obviously, Mac's neutral special is pretty worthless in all three variants); people are seriously just not adventurous at all or willing to take "risks" on the character select screen. Several players were interested in the idea and thought particular custom moves on their character might be worth it but did just have that mentality of not being willing to go for it unless they were sure in the first place that a move was right to use and were fully prepped with that move... not that anyone is fully prepped to play a game that's a month old anyway.
I don't really know how to respond to that; my mentality has always been about really going for it to use anything you can get your hands on. Just declining to use the customs when available as the most common response to them being legal is... weird, though after the event I played a fair number of friendlies showing stuff off and exploring how some of this stuff would play out and definitely imparted the value of MK's high speed drill (made a passable case for Dreadful Tornado even), Mario's Explosive Punch, Mii Brawler in general, and also was showing off our recent frame data work to discover on the spot that Rock Hurl has super armor from frame 1 which makes that previously lousy seeming move suddenly quite compelling! I kinda get a sense that customs are the sort of thing that will need time to grow on people maybe, but I'll definitely be thinking of the secondary communication challenge beyond "here's why they should be legal" to "here's why you should pick some of them when they are legal".