It's difficult to interpret what you are writing 'well it isn't proved if that's what you mean it is theory so it could be wrong' to answer any of the questions.....perhaps you agree, dark matter/energy is not proved so its probably in error or its 'theory' or belief is not 'truth'.
science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/
Not relevant to expansion???? Dark energy and dark matter are inventions of their mother-expansion...
science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/
Snell's Theory states contraction at an ever increasing rate is happening...Einstein's GR and equations are not in error but the (Hubble)'redshift' interpretation to mean 'expanding universe' and subsequent 'dark matter' to explain expansion is in error. The only plausible theory which is provable and having observable evidence indicate contraction at an increasing rate, rather than expansion at an increasing rate and dark matter etc...
Good, you agree it could be wrong.... Now think of the universe as contracting at an ever increasing rate.....does that solve a lot of the issues facing cosmology/astrophysics while negating the expansionist theory and need for ideas like dark energy and dark matter???
I have a grasp on the expansionist theory as well as GR and STR etc, expansion fails to have merit. There is no more to know about expansion except that it fails to have explanation except by means of unproven dark matter/energy etc nor does it match observable contraction/evolution/evidence...... your 'criticising' is spelled criticizing 'learn a little more'.
Great, you agree
Good, you have the right idea, expansion is a theory which may (is) wrong. If contraction is what the universe is in a state of, how does expansion theory explain it? How do expansionists explain their current belief that the universe is expanding at an 'ever' increasing rate??