most tuning solutions have cylinder trims, also manufacturing tolerances, its very reasonable that they are all on the verge of doing it and the one simply has a little excess resistance or something that pushs it over the edge.
its the same reason engines go boom all the time from detonation but you only see it on one or two cylinders because the engine was on the ragged edge. theirs literally no less then a couple dozen reasons why only one would go on a tune.
float_6969 wrote:If it was the tune, why would it only continue to damage one coil?
This is an electrical issue. Have you tried changing plugs?