OK but...
1. It's OTAs. It's the perfect time to figure these things out
2. They have two years of Cleveland at Guard, including camp, preseason, and regular season. Feel like they have a good idea of what they're getting there. His ability to provide positional flexibility could, quite literally, be the difference between whether he makes the team or not. He's certainly not guaranteed a roster spot. If he had the LG job locked up, he wouldn't be working out at RT.
3. Basically same as #2 for Faalele and Sala, but the opposite spectrum. What is Faalele's path to playing time as a Tackle? He's basically the #4 tackle heading into camp. If he can play Guard, he can either a) start there or b) backup there. Even if he doesn't win the starting LG battle, if he shows well enough, he's now the top backup at Guard and top 4 Tackle on the roster. That's valuable.
Sala is literally a rookie who's never played a snap in the NFL, and was a late round pick. If he's only here as a Tackle, he has literally no value for the '23 season whatsoever, and very little for next year. He's, what, the 5th tackle, at best? I don't even know if we can carry like a 10th offensive lineman who can only play on position.
Basically same mindset... your depth Olinemen have to be flexible. There just aren't enough good one's coming out of the draft that you can take a 5th or 6th rounder and think they can only play RT. They may settle in later in their career to that level, but that's just not a luxury NFL teams have.
You said yourself... if these players were high end players at their positions coming out of college, they wouldn't have been late round picks to begin with. For all we know, they've been playing out of position in College. Happens all the time.