I think there is a heartline for the zero-g roll, but no heartline for the in-line twist, I'm trying to work it out, but is it possible they vary the heartlining?
Look at LC12's zero-g and wingover for example, they look like standard (albe it drawn out) B&M elements which I would've thought required a heartline. If you look at the diveloop drop there does appear to be some form of heartling as the track moves off to the right to allow for a twist to the left. It is very slight though. Then the final in-line appears to have no heartline at all.
Confusing. But my conclusion is that the track is heartlined, but the heartline is directly in the center of the middle part of the train so is fairly low off the track, APART from the element which I would like to name the "non-heartline roll" =). It's going to be quite annoying to recreate using Newton...but I love a challenge.