Arduplane mavling pitch with Storm 32 bug?

I do not know if that is a bug. Not many people are using mavling during an Arduplane Auto mission where there are ROIs determined for the Storm 32 controller aiming the SBG.
I am using mavlink to have the Pixracer communicate with the Storm 32.
If I set these parameters like this:
MNT_ANGMIN_PAN = -18000, MNT_ANGMAX_PAN = 17999
MNT_ANGMIN_ROL = -6000, MNT_ANGMAX_ROL = +6000
MNT_ANG_MIN_TIL = -9000, MNT_ANG_MAX_TIL = +9000

My camera points too low.

I have to adjust the parameters like this to have the camera point with the right pitch:

Storm 32 Pitch settings:
‘Rc Pitch Min’ => 120.0 °
‘Rc Pitch Max’ => -90.0 °
‘Rc Pitch Offset’ => -49.0 °

MNT_ANGMIN_PAN = -18000, MNT_ANGMAX_PAN = 17999
MNT_ANGMIN_ROL = -6000, MNT_ANGMAX_ROL = +6000
MNT_ANG_MIN_TIL = -11000, MNT_ANG_MAX_TIL = +11000

I always set the ROI altitude relative to the height of the flight. If the plane is 100 m above the ground circling the ROI, the ROI altitude is set to 0.
To have the camera actually point with the right pitch, I need to adjust the Storm 32 pitch offset in the Storm 32 gui. That way it uses a good pitch angle if I am 100 meters above and away from the object, but the further the plane is, the more is the camera looking up in the sky.
Is this supposed to be a bug that the arduplane is sending wrong mavlink data to the Storm 32?

Version
Arduplane 3.8.4
Storm 32 v0.96
Platform
Plane
Airframe type
Motorised glider
Hardware type
Pixracer,
Logs
Will add one if needed. This situation is easily reproduceable