Do you remember vCoH panzer elite Pz4 (the one with the stubby cannon) that could get into stationary fire mode and receive extra firing rate. Would that mechanic a good way to buff comets?
No, as the Comet is supposed to be the opposite of the Churchill and act as a mobile tank versus the slow meatshield.
Things to address:
Veterancy: The unit needs some form of offensive veterancy to help it engage targets later on. Few, if any other vehicles have 0 bonuses to either reload, or penetration. While the Comet does get accuracy, its firepower for the most part is the same from stock to veterancy 3.
One might count on the auto-grenades as a substitute, but then you're getting in close and it doesn't help vs most vehicles that the Comet will engage.
Moving Accuracy: With the current state, I don't think returning its 0.75 moving accuracy would be terrible to emphasize its status as a mobile tank as that's its whole point.