I cannot understand what exists between my words and my sense. "still" is out of place in this assessment, because as I said twice, the bonus applies to them and to melee units. I will throw every piece of information I have at this now.
To understand how it treats them differently you have to know how combat works, which I skipped over because the original question was confined to Heroic Epic.
When ranged units attack ranged units, they (for some reason) compare ranged strength to the ranged strength of the archer/gun. This is the only time between units that ranged strength becomes defense. There is further a modification for hit points , and a further modification which, on top of the attack type peculiarity just mentioned, makes ranged units and melee units especially susceptible to each other's attacks but better at defending from their own ilk.
I don't know how bombard defenses work, but I know the cover promotion doesn't function against it (it is actually bugged in even its simple case).
The Morale promotion gives a modifier. All modifiers apply to the strength, so they are additive, not cumulative. And the strength concerned will vary depending on who is involved in the combat.