typical
" 3) The traveling twins must also witness 12 earth years/orbits or all mainstream astronomical observations are false. ",
except the traveling twin is no where near earth nor in the same reference of earth time.
you fail acknowledge that you are trying to implement earth time to high rates of speed time in space.
" 6) Therefore SR and GR are false because they contradict proven mainstream astronomical observations. ",
actually no. not at all,
what has contradicted proven mainstream astronomical observations is your understanding of,
and it's obvious you do not understand orbital mechanics if you actually know it exist.
it's as simple as this below,
time stretches and space shrinks when an object moves at a high velocity.
in time dilation, the faster an object moves, the slower time passes.
SR describes how the universe behaves when an object is moving, called time dilation.
which forces time to go more slowly for you(relative to stationary people)the faster you travel.
if you are traveling at c , 0 time passes. time is frozen.
time is reluctant to change except at high speeds
cosmos doesn't have a single inviolable size.
if you could go at light speed to see what photon experiences,
there would be no distance at all between you and the farthest edges of the cosmos.
you would find your self everywhere at once
imaginary time is a way of looking at the time dimension as if it were a dimension of space
time dilation, the faster an object moves, the slower time passes.
time stretches and space shrinks