Ambush says "single target ranged weapon" but works with burst fire. "Single target" and "AoE" simply refers to the damage zone of each individual attack, not the ability for targeted attacks to spread for certain weapons.
I understand the terminology could be clearer, but there isn't really an encyclopedia feature in the game and it probably doesn't make sense to build one at the moment. It could be something to add in a future Underrail title, but for now the wiki probably is the best thing we have.