scoring question
 

This happened tonight in our NFHS match: R1 indicates a point for Team A, when the point was actually scored for Team B. R1 just pointed in the wrong direction. Neither R1 or R2, or scorekeeper realized it. Team B scores 3 points before the scorer for Team A asks the R2 about the "wrong" point. R2 says it was too late to "fix it". Is this the proper procedure? Why wouldn't you correct this mistake by removing all points scored by Team B, award the point to Team A, then allow the same Team A server to continue her service?

The closest that I can find is 11.3.1 Reviewing Decisions:

Which indicates that a coach may request a time out to challenge a ruling by the first referee. This must be done during the dead ball immediately following the incorrect decision.

So I would agree with the R2 in your OP, the incorrect decision of awarding the point to team A to team B cannot be corrected 3 points later.