That sign (in the picture) is inaccurate/outdated for few reasons:
1) Kuwait Airways ceased its operations between KWI and KUL.
2) When I flew Royal Jordanian J class I was directed to MAS golden lounge, and not the Plaza Premium Lounge.
3) Since when did Qatar Airways use Plaza Premium lounge as opposed to MAS golden lounge?
I agree with you, downgrading the lounge from MAS golden lounge to the plaza premium lounge without cutting the J fares is in poor taste.