I've installed many pocket doors and owned a few. I don't recall ever having to tighten a lock nut. It's awkward enough getting the little bent wrench in there to adjust the thing in the first place.
As I recall there are detents built into the adjuster. They may be at the bottom of the bolt where it engages the door mounting plate. When you rotate the nut, it should feel like it's clicking into notches. The weight of the door itself locks position in these detents.
Either that or there's a nylon insert providing friction. In any case, I recall some of them being rather stiff to turn.
Therefore, I doubt that a loosening adjuster is the cause of your problem. Firstly, there should be enough of a gap under the door to accommodate seasonal movement, etc. If there isn't say 3/8" to 1/2", and you're out of adjustment range, I would shorten the slab. A power planer or circular saw would do that job, followed by a small chamfer with a sander. Tape the surface first to prevent splintering.
Then, if things are moving that much, look for sag in the head frame. It's usually suspended from the rough opening by sheet metal straps, but maybe they weren't attached properly. You could firm it up with long screws judiciously applied.
By the way, you can probably find the manufacturer info by dropping one of the trolleys out of the track. Most hardware has a mechanism to allow removal of the door (detachment of the trolley from the door bracket). In your case there may be a rotating catch on the door mounting plate which locks a ball or tab in place. Once you detach the trolley and rest the door on the floor you can roll the trolley to the end of the track and tilt it out the gap between the end of the track and the jamb.