Soundslice just displays whatever tempo was in the tablature file. I don’t recall paying a whole lot of attention to what tempos we even notated back then, because I didn’t think it mattered. We weren’t trying to say you needed to play these examples at that exact speed in order to be correct, we were just trying to give you an example of the motion to look at as a reference. The tempo was an afterthought.
More recently when we transcribe interviews we do try to get the tempo markings close, because it’s data about how the player’s technique works, and it’s something we can learn from. i.e. Some players play certain lines at certain speeds and other lines at different ones. It’s still just a ballpark though. If a player speeds up and slows down during a clip we don’t usually notate that super specifically, but we’ll include a fermata or ballpark tempo ramp if we think it’s important.