GR00T: This strikes me as an inadvertent design bias, where the developers play the game a certain way and are so used to doing it that way that they don't consider other players may go about it differently.
Yeah AOE3 has some quite rigid triggers in some of the missions, it seems.
So in this mission, I did that now, did everything I could expect build a town center (which is usually the first one you do when building your town). I used my existing villagers to gather resources, built those buildings I can without a town center, and build lots and lots of lower units like crossbow men.
Something still triggered the enemy to send some troops (maybe it was that I went too close to their base), but it became kinda funny that those troops wouldn't attact the Aztec temples just because I had not build a town center. Massive enemy troops just circling around the temples, not touching them.
Then I just experimented all kinds of stuff, like trying to fight those troops wiith my low level units, and even attacking the base. That almost worked, somehow I was able to destroy 80% of their buildings but suddenly the enemy sends all its troops from the temples to the homebase, and they wipe out my lower level troops.
So if I try this "delay the town center"-trick in order to prepare, I need to kill those troops patrolling near the temples with huge armies of low level troops, and then build the town center right when they are cleared, and try to advance to new ages etc. to upgrade further and get better troops etc. It does feel that I am just trying to trick the enemy AI in order to succeed, using those triggers I know.
I need to change my tactic a bit though, maybe using cavalry instead of the crossbowmen because the enemy starts sending lots of anti-infantry artillery (+cavalry) which wipe out the archers and other infantry away quite fast.