There's actually a given height for Sokovia, so no need to assume it to be a hemisphere.
Destruction of Sokovia
I think we can assume Sokovia to be half ellipsoid?
2380 feet = 725.424 m
Mass = 2/3*pi*976.884*976.884*725.424*2800 = 4.059705759030368479042672091287755e12 kg
4.059705759030368479042672091287755e12*977.81^2*0.5 = 1.94076750036374740958170092367e18 Joules, Mountain level
Now plugging the new number into the original formula.
1.94076750036374740958170092367e18/2280.55750546*1.14 = 9.701465300119255897112988088e14 Joules, still Large Town level
So Thor is still Large Town level.
Iron Man's Durability
I suppose we should first Inverse Square Law the destruction of the city first before dividing by every single square metre?
Robert Downey Jr is 1.74 m and around 68 kg according to a quick Google search, that's around 1.818 m^2, multiply that by 40% to get a cross section of 0.7272 m^2.
However when with his Iron Man suit on he is 6'5" tall or 195.58 cm. I guess I'll still use 68 kg as the weight? Since using the weight of his armour is inaccurate for that calculator. That's 1.979 m^2 or 40% to get 0.7916 m^2.
1.94076750036374740958170092367e18/(4*pi*725.424)/2280.55750546*0.7916 = 7.38986466713003010462792629815207173930391123771416e10 Joules, City Block level
Might be an outlier, idk