Advice on a wireless fencing scoring system?

I have never used 433 MHz wireless so you will have to wait for someone else to help with that. AFAIK it is a lot less sophisticated than an nRF24, but, as you say, it does operate in a different frequency band.

You have not answered my request for "details of how often data needs to transfer from a slave to the master". That is important whatever system you use.

...R