Following up on this, I didn't find further description or explanation on the v17 manual.
Also, I've tested the previous transformation (the most common we'd use, from DCI P3 to Rec709) against the newer one, and found that now it is indeed slightly "more greenish".
I haven't get into dissecting the other aspects of the different possibilities when converting (either with Color Transform or through Color Management), but I'd appreciate more information.
It's a bit worrying the lack of description when the tool we are using for color management is modified. This kind of makes me want to go back to our LUTs in nodes for controlling all the color transforms...