I recommend these articles:
Wikipedia: "Master-slave technology: Terminology concerns"
WIRED: "Tech Confronts Its Use of the Labels ‘Master’ and ‘Slave’".
and I was surprised by how many different technologies use the wording: mechanical engineering, computing, creative media production...
It looks as if there was a notice at JLR but I can't find what it actually said.
Surrogate is a very poor surrogate.
Leader/follower and primary/secondary would work in many settings.
Primary/replica puzzled me for a bit: I think that it came from production of creative media and that it would work well there but not for hydraulic cylinders. I don't expect mastering or master copy to disappear in the near future.
Or master/slave.
Jonathan