How to use 360 stabilization on VR180 2D with black bars?

I converted a Gopro Fisheye video into a 2D VR180 at 3484 x 3484 pixels.
As this is shaky, I loaded it into shotcut to use 360° stabilisation.
The problem is, the shakyness is hardly compensated for.
I wonder how to use the 360 for custom VR180 2D videos like the one mentioned that do not cover the whole 180 x 180° but have black bars.

This filter is for 360 equirectangular projection video only. You can try the regular stabilize filter.

Thanks.

Is 360 required or is it only necessary that all 3x9 boxes cover footage?

Because it is equirectangular projection, but not 360 and instead 118 degrees with black bars to fill up to 180.

The normal stabilise does not stabilise it well, so it’s shaky. Here the virtualdub filter deshaker is more precise.

But both normal filters are worse, because they don’t take the spherical nature into account, which creates a distorting effect.

How come?

Push

Do not nag.
Obviously, a spherical image requires a spherical rotation instead of flat shifting and rotation.
Here is the source code for the 360 filters, and I did not write them so I am not going to be of further help: bigsh0t

It is better if you use a camera that records gyro sensor data that can be used to calculate the rotations needed to stabilize as used by