There are at least 7 major axes.
Polar Axis and Equatorial Axis - Horizon plane
Equatorial Axis and Aloft Axis - Equatorial plane
Polar Axis and Aloft Axis - Meridian plane
Ecliptic Axis and Equatorial Axis - Ecliptic plane
Anti-Ecliptic Axis and Equatorial Axis - Anti-ecliptic plane
Also ETA(equator towards anticlockwise) Axis and ETC(equator toward clockwise) Axis
Its incosistent to describe the cosmos motion with only one or two axes.
Don't forget the all-important axis that connects Portlands Oregon and Maine! Except nobody claims the Earth rotates around the Portlandic Axis.
Seriously, though, I get that two non-parallel axis can define a plane, but the Earth rotates around the polar axis (that is, connecting the north and south poles), not any other axis. When depicting a rotating sphere(oid), you need only the axis of rotation. That axis, while it
does wobble, a complete rotation of that wobble takes about 25,000 years (one day, Vega will be the pole-star, which'll be nice because Vega's a whole lot brighter than Polaris).
You say U and L are points which are defines as being points on the Tropics of Cancer and Capricorn respectively. These tropics are perpendicular to the polar axis (that is, the axis connecting the north and south poles). They, and the equator, are points where these three parallel planes (the Tropic of Cancer plane, the Equatorial plane, and the Tropic of Capricorn plane) intersect the Earth. Once again, they're
perpendicular to the polar axis.
Yes, there is an ecliptic plane, but since you're arguing in the heliocentric theory, it would best be described as centered on the Sun, upon which the Earth-Moon Barycenter
[1] always resides. The Earth
orbits on this plane, but it does not revolve around any axis perpendicular to it. In fact, any axis perpendicular to this ecliptic plane (that is, an axis around the Earth) might be useful as a coordinate system, but is irrelevant in the rotation of the Earth.
Because the Earth rotates on the polar axis.
If you can show us a model of the Earth rotating on the polar axis and still show there should be four seasons every 24 hours, I will gladly and happily join with you in denouncing the heliocentric model. But that rotating Earth model has already been created
[2][1] The Earth-Moon Barycenter is the center of mass of the Earth-Moon system. I say this orbits the sun because, just as the Earth pulls on the Moon, the Moon pulls on the Earth, causing it to wobble. This wobble is around the Earth-Moon Barycenter.
[2] See the model above