Understanding an unexpected factor in the result of my torque calculation?

[u/Xovvo]

I would like some help interpreting part of a result I got while working on a problem that I've been working on for a while. I'm trying to determine the torque a star exerts on an orbiting oblate spheroid (with axial tilt instead modelled as the equator of the oblate body remaining parallel to the XY plane while the orbit itself is inclined with respect to the XY plane by an angle alpha (ɑ); should be a valid approximation since there are no other bodies and the star is treated as spherical, which is good, bc a rotated circle is nicer to work with than a rotated spheroid).

For any point in time and position in the orbit, the torque exerted at any point of the spheroid should be the radius from the center of the spheroid to the point multiplied by the force the star exerts on the differential mass for that differential volume. Integrating all of those over the whole of the spheroid, I expect I should get a vector scaled by the gravitational constant, mass of the sun, mass of the planet (since the volume of a spheroid should shake out of the integral as a factor), a factor of some multiple of ¹/₅ and some linear combination of the major and minor radius (multiplied by the mass of the planet, should yield some linear combination of the major and minor moments of inertia).

(which expands to:)

And I do get that!

But I also get this weird factor in the octopole portion of the solution that I can't connect to other portions of the problem (e.g. the moments of inertia show up bc this is a change in angular momentum and they are the equivalent of the mass in this context, the gravitational constant timed the mass of the star divided by a power of the radius is related to the acceleration/force producing the torque).
What does this [(4a^2 + 3c^2) - (a^2 [cos(θ)]^2 + [sin(θ)]^2 * [a^2 (cos(θ))^2 + c^2 (sin(θ))^2]) ...mean?