You are expending some great effort to sort out your problem
However, an ignition coil that is shorting when hot may not be found when it is subjected to external heat source. The internal heating generated while being used is different as is the potential for shorting. When testing with a meter, the test voltage is usually 1.5v. When in use, the voltage is 20Kv.... it can arc thru poorly insulated wire.
I'm not saying any of them are bad, just that an ohm test is not that good for a problem like you are having. A bad resistance reading will confirm a bad coil but a good resistance reading does not mean the coil is without fault. Swapping between cylinders to see if the problem follows is a better test.