No of course the UK is the only country in the world that operates overwater, night IFR, SAR - just ask Crab. He is the one with who has extensive world-wide civilian SAR experience in the AW139
I have at least flown a SAR 139 over the water at night
Apart from the fact I don't like the transition profile in light winds, it is more than capable at night now - it's just that what was accepted by the MCA and CHC a few years ago wasn't fit for purpose as the lighting was inadequate and the SAR modes for the autopilot hadn't been certified.
AFAIK the 189 is just a 139 with a plug in the fuselage to make it longer so it should breeze through certification and be at least as capable as the 139.