Do they have to trigger in order? Ex: if I find a 2 symbol before a 1, do I keep going until I find a 1, trigger than and then find a second tile with a 2 symbol to trigger that effect?
The Numbers are only there to distinguish a difference! (It usually also means in order of importance as well as frequency of trigger, more 1's than 2's more 2's than 3's)
So, to answer your question specifically, No, you don't trigger them in order, you Trigger them AS they are Explored!
As soon as you trigger a Scenario 2 Trigger Room, trigger the appropriate thing!
However, some scenarios DO want you to Trigger those Specific Triggers in order, because sometimes, a specific part of a Symbol triggers only once.
Scenario Trigger 1 (1st time: DO THIS) (2nd time: DO THAT) (3rd time: DO THIS) each additional time after it does THIS (or nothing)
Let me know what other questions you might have!