so something is wrong with tilt? not with the y-coordinate?

edit:
yeah! that's a bug...

try to add a minus to o.RotY in this line:

file.write("\t%f %f %f\n" % (o.RotZ * RAD2DEG, o.RotY * RAD2DEG, o.RotX * RAD2DEG))

needs more testing though. could be more complicated to fix if blender's rotation order turns out to be different to gamestudio's.

edit2:
the rotation order seems to be the same. adding minus should be enough.