My solution when AIs move abnormally in the formation flight.
*This is based on my experience, so it's okay to refer to it without using it.
Much of this phenomenon is caused by the lack of an element of the engine hook.
According to the log, Ki-48-II of BAT Stock ver also does not have the engine hook values of the 'Engine1ES_02' and 'Engine2ES_02'.
Putting these values in the engine hook position of 'Engine1_DO', 'Engine2_DO', then it maybe solves the problem.
But the question is how to set the values.
I'm not an expert, so I can't make these values exactly.
So, if the modder made this aircraft by modeling it on a plane, you can use its engine hook from the original model plane.
If he haven't, you can just use the engine hook values of 'Engine1ES_01', 'Engine2ES_01' (copy and paste).
This will almost solve the problem.
Thank you.
PS: the reason why I'm trying to keep using Ki-48-II of BAT Stock ver, because it(New 3D ver) still don't have enough skins available.