Armor values are visible to all in the main interface. Same as HP. No Loremaster required. So the AI uses the same info as player. That is correct.
Wrong is MA/PA mechanics and hard cc chains.
You can't tell if a character has glass cannon just by looking at their armor values. Maybe you could argue that enemies could deduce it based on your AP usage in a turn. That would require you to play at least one turn, though.
making the AI variable is a difficult to implement (for larian) yet an exciting prospect (for us). Going off your leadership idea it could be an AI specific talent which you can see through examine OR be an aura specific units put out. The former is better for the stats nerds like me but the latter is better for the general player. An idea of my own is to have it linked wits meaning you can tell whom the leader is through turn order.
I think it's not as complicated as you think. Mostly they could just add one more condition (leader in range, status applied, intelligence level, etc.) to existing AI behaviors. It's not always that simple, but they're already attempting much harder things by actually making intelligent AI. Making those AI take steps down from peak smarts is much easier.
I don't feel like a leader is necessarily the fastest person in a group. "Wits" implies personal cleverness and awareness, but not necessarily the capacity for leading other people.