I have problems with a few of your arguments
I don't think that is quite true. The flat earthers held a belief that was at odds with the observations that were available to the ancient Greeks. Their beliefs WERE fully in agreement with simple observations of the world around them.
And solid earthers can be shown observations and infact we may soon have cameras capable of showing QM behaviour much like IR cameras.
But even though QM shows that there is nothing really "solid" the observations that we make of the real world are still true. We still observe a solid world and that world works just fine.
How do you reconcile that any observation you and I make are not identical via Bell's inequality or are you taking a non scientific version of observation as per what a human eye sees?
When we started traveling around the world the flat earth theory was completely undone. Nothing has caused any change in the solid world theory. Their are changes in the explanations of why the world is solid, but for almost all practical purposes we can still work with solids.
True currently until you take them down to very cold temperatures where the solids become very unsolid and even superflow and appear not to be there as the QM effects really start to manifest.
To me your argument seems to centre around the word "observation" and what it means.