A constantly accelerating earth would almost match what we observe in reality. The fact that a feather falls more slowly than something more dense would be caused by the same phenomenon, air resistance, because as I understand this hypothesis, yes the air is moving with the earth in an enclosed dome.
As I said though, it would only ALMOST match what we observe in reality. The one glaring piece of evidence that comes to mind is the fact that gravity at the poles is stronger (AKA accelerating faster in flat earth hypothesis) and the closer you get to the equator, the weaker (slower in FE) it gets.
This difference is quite small, roughly .5% difference between the poles and the equator, so you wouldn't notice it just walking around (you would notice the different weather though, LOL). A 200lb person at the north pole would roughly weigh 199lbs at the equator. Elevation also plays a role, albeit a more minor one. Higher elevations tend to have weaker gravity than the surrounding lower elevations.
This may not be noticeable in day to day life, but it is however not an insignificant difference. For the various FE models that claim earth is accelerating, it spells disaster. It doesn't take long at all for the earth to rip itself apart under these varying forces.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/grl.50838EDIT:
As a side note. The notion of an accelerating earth as touted by many FE'rs doesn't seem to line up with zeteticism.