I would not be surprised if this whole mess is just a personal project of David Curtis wanting to change everything for some reason. He got the job as their Onboard Systems Service Delivery Manager (basically a fancy term for PIS manager) in early March 2023 and then around three months later at the end of May 2023 and beginning of June 2023 was when Peter Corley started replaced Trisha Jarman and all this mess and constant changing of scripts and voices started. So i think it is very obvious that David Curtis is the person responsible for this mess that their PIS has turned in to. It can not just be coincidence that everything started being messed up as soon as he got the job managing the PIS on their trains.
If he is in charge of the destinations on the trains too I wonder if it is him that has come up with "See station Displays" instead of just showing Not in service or the destination on the train CIS, its a waste of time because the station screens are always wrong as well because of the garbage Ketech system! Train says "See Station displays" Screens erroneously say "This train does not stop here" when it clearly does! The passengers are so confused by it all. Either that or "system rebuilding"
As you say It sounds horrendous now with different voices doing the same announcements.