I like to think that the pretentious terminology might soon be scrapped, and a spade called a spade by the management once again! The crews probably have no interest in using it because it seems pompous and prissy (and not at all ’railway’), whereas ’first’ and ’standard’ are universal across the industry, and the sleeper had a ’lounge car’ for nearly 30 years before anyone felt the need to rename it. I have also heard instances whereby passengers with ’club’ tickets were, at least initially, refused access to the Euston first class lounge because they didn’t say ’first class’ on them. While I hope that this has now been rectified with staff training, it does go to show the issues caused by non-standard terms (and why they’ll never endure).
I'm not sure what stories you were hearing, but the "Club" ticket I was issued recently has "1st class" on it.
It would seem odd for that to be a new addition when it would be much easier just to say to staff "You know how we let Caledonian Sleeper passengers in? Make sure it says "Club" or "Double" on their ticket".