Smoked HEI coil.
It should not affect the module IF it was a GM HEI. EXCEPT what you have is NOT a real HEI. There is only ONE HEI and that is GM HEI, so here's the deal:
YES a grounded tach wire could ruin the coil HOWEVER
Some ignition systems cause the coil to draw current when powered, you should NEVER leave the key in "run" for any length of time
Points, if points are closed, will ruin the coil AND the points
Mopar factory breakerless, can ruin both the coil and module
Pertronix, I BELIEVE draws current this way so it is also a fail risk
The system you have? I am not familiar
AND FOR THE GOLD:
A properly operating HEI module DOES NOT draw current with the key left on!!!!