Also, if they follow the model from before, should this line be the grenade launcher?
A lot of people think the auxiliary weapon is placed in the same as the 2A42 was placed on Objekt 195:
The protrusion you highlighted is actually symmetrical, there's an identical protrusion on the other side. This leads me to believe that it's either part of the wood frame, part of the APS, or some sort of sheet metal plating like what the T-90SM has.
There is another possibility, it could be auxiliary weapon mounts, minus the guns themselves. This has been overlooked, because without the guns it's not obvious. But if you look at the other vehicles, the Kurganets BTR variant doesn't have the gun fitted to the RWS yet.
Anyways. The red line on the bustle and circle on the mast indicate the limiting points, we know those are boundaries. The green line indicates the peak of the smoke launcher The blue line is roughly were the 2A42 may be located if it's mounted similarly to Obj. 195's 2A42.