And to further clarify, a radial with four cylinders can also have an even, alternating firing order, 1c,2e,3c,4e,1e,2c,3e,4c....with simply a two-lobed cam, alternating cylinders actuated from opposite lobes, so that is an even firing order, but still doesn't work in a radial, because you can't still achieve a lockup condition where you have opposing pressure forces--my whole point, you can't have an even numbered radial due to angular spacing and resulting opposition--but firing order or cam timing are a secondary issue, NOT the primary.
1c,2e,3c,
4e,1e,2c,3e,
4c,1c,2e,3c,
4e,1e,2c,3e,4c, is uneven. No way to make it even in a 4-stroke setup. 2 revolutions per cycle means the number of cylinders must not be divisible by 2 if you want evenly-distributed power. This ONLY applies to a radial because the cylinders share a single lobe on the crankshaft and therefore their TDC order is fixed and sequential. This is in opposition to multi-lobe crankshafts where you set up different cylinders to have synchronized TDC timing, but opposite combustion cycle.
Here is away you could have a 2-lobe 4-piston-per-lobe radial engine, with an even power distribution as a whole, but unbalanced distribution per lobe. You make the double-power and double-exhaust strokes cancel out
Disc1: 1c,2e,3c,4e,1e,2c,3e,4c,1c,2e,3c,4e,1e,2c,3e,4c,1c,2e,3c,4e,1e,2c,
Disc2: 1e,2c,3e,4c,1c,2e,3c,4e,1e,2c,3e,4c,1c,2e,3c,4e,1e,2c,3e,4c,1c,2e,