I have a copy of the AW189 OSD (issue Oct 2019 rev D) and the MDR levels listed in there are E/E/E for pilots converting from AW139-AW189.
I know that Leonardo used to do specific AW189 TR courses for AW139 rated pilots, they more than likely still do but better to ask them directly. If I remember correctly it was about a 30% reduction in ground & sim training compared with a full TR.