Something that AW has done a lot of in the past which irks me a lot is that they love to mix flavor text within the rules. This can "bring things to life" and help things "make sense" but they can also be misinterpreted as rules in their own right. Separating out useless text can be a kind of art form, and is in no way an exact science.
With that in mind, I agree that you should ignore the part in parenthesis. In several other places they define those symbols as meaning they don't work against melee or they don't work against range, and that's the definition I would use. Really, if you try and interpret them as meaning they only work against range/melee then their design and the way the rules are written don't really make any sense.
Thus, I'd say that all of your example defenses would work against hydrothermal vents, and that is the one weakness it has compared to other traps.