Yes. As a general rule, whenever the rules say "X deals damage to Y", it is simply specifying what you're allowed to assign the damage to; it does NOT mean "to each Y". Eg: "5 Damage to [Town]/[City]" = "5 Damage allocated as desired among Towns and/or Cities in target land", NOT "5 Damage to each Town/City in target land".
Anything which does damage to each-of-a-thing will explicitly use the word "each" (or "every", or "all") - "to each Invader", "in every adjacent land", "destroy all Invaders", etc.
The confusion arose from a combination of things, the standard targetting is by land, so first inclination is to select a land, but the plural lands broke with that, leading to either things targetting by something other than land/spirit, or it meant multiple lands being selected for the full damage. The dividing up of damage is non-standard in this game, so it wasn't how we read it.
I was expecting that the wording should have been "an adjacent land" as that makes the most sense from the game's normal mechanics.
Wording it so "divide" is in it, or making it clear you select for each invader would be the best wording, but that gets significantly longer.