Rotation fault caused by libero replacement

[Scrapper1]

Ok, this is a multi-layered question, so please bear with me.

I worked lines opposite the scorer's table tonight for a high school playoff match that uses NCAAW rules.

In the first set, the Libero was in the back-left (in the 5 position) and the Libero's team won the point. She would normally have to be replaced, as she was about to rotate into the front row. Instead, she moved to serve the next point. Everything is ok so far.

As she is preparing to serve, a player comes off the bench and moves into the libero replacement area and a front row player moves toward the sideline. They are going to do the normal "double switch". But before they can do it, the R1 blows the whistle and beckons for serve. The two "switching" players hesitate and then do NOT complete the replacement. This looked wrong to me at the time.

Libero serves and wins the rally. At this point, the R2 stops play and has a discussion with the table. After a few moments, he turns and gives the court back to the R1, assessing no penalty or anything. The Libero then wins the next 2 or 3 points (I can't remember exactly how many).

Question 1: Would someone please walk me through exactly how this is handled? I'm pretty sure this is a rotation fault and that we can "erase" all the points that the Libero serves, but I'm really not confident that I could get it right in a real match.

Question 2: As a linesperson, can I bring this to the attention of the R1 or R2? Or do I have to just bite my tongue (which is what I did, by the way)?

Any help on this will be appreciated.