Maybe NFHS doesn't address a time limit because they can't think we'd possibly be that careless.
As officials, we're supposed to notify a team when they are out of time-outs (well, the scorekeeper notifies the coach THROUGH the officials, but that's us right?). Then all the officials should know as well as everyone at the scorer's table. If we've done our job and one team calls an excess time-out and none of the game crew figures it out until after the ball is back in play..... how asleep at the wheel are we?
In that case, I'd say play on and let the opposing coach give us a couple lashes with a wet noodle.
Z