NFHS switch
 

It's been two years now, and it seems every game I have there seems to be plenty of interpretation on lead/new trail scenarios. Simply put, so I can remember, trail is always trail and reports and goes back, or the only time you switch is a TC or PC foul called by lead. Additionally, if a shot goes up and a foul incurs on rebound with no team control, you are still lead so a switch would happen. Am I correct by definition? Conversely, as soon as defensive team gains possession, and is going long you are trail.

Correct. It's really not that hard to understand but it is hard to teach old dogs new tricks.

Where's your book?
 

Sounds like you are talking about when to switch after calling a foul in two man.

In a nutshell, if you are trail you stay trail and if you are lead you stay lead unless we are shooting freethrows or going to the other end of the court. If shooting or transitioning we switch.

In my state we do not do the "long switch" but your state may vary.

Lead: Go. Trail: No.

Or, Old Trail remains New Trail, Old Lead becomes New Lead (which doesn't really work, because L could become C)

The only hard part is for the non-calling official to know whether the foul was "during" the rebound or "just after" TC was established..

Agreed. That's the problem.

So the calling official needs to recognize that and say to the old table-side official "I'm going back" or "I'm staying here" (or words to that effect).

(Often, you can just make eye contact and give a little wave or head shake / nod to communicate it.)