Front row libero

[MCBear]

1. Should the libero tracker have notified me immediately by sounding the horn? At what point should the LT let me (R2) know?

Absolutely! The libero in the front row is illegal once the serve is beckoned/contacted so the LT should notify you on contact.

2. What is the violation? I could not find any specific mention of a penalty for the libero playing in the front row. Through inference and assumption, the best I could come up with is an illegal replacement.

Illegal Alignment/Out of Rotation since the Libero is not allowed to play in the front row.

3. Besides being more aware and catching it in the first place, what should we have done with this situation?

That's about it except for having your table people working with you.

BTW, the Libero replacement during the time-out was illegal since an exchange is not allowed during a Time-Out and should have been sanctioned. Since you caught the switch after the Time-Out, the illegal replacement should have been sanctioned with an Unnecessary Delay Time-Out. Per Rule 10-4 Penalty #1:

PENALTIES:
1. Unnecessary delay is charged to the offending team when an illegal libero replacement takes place prior to the whistle/signal for serve. If identified after whistle/signal for serve, illegal alignment results (loss of rally/point). In all cases, the illegal libero must enter legally or be replaced by a legal player.