You do not.
That's it. I have tracked my Constructs city for 24 rounds of 64 corals. My Halflings for 20. I have gotten numbers from another FS. I don't have all put together with mine. But as i have that many numbers to look at now. There's not a fixed order.
The first two are the same.
The following 8, switches each between two quests. Which one you will never know. They randomly switch each of those 8 quest, which gives an insane high number in possible outcome.
You do know. It's not a totally fixed order, but somewhat of an order, with a random opponent still in place. So you know which set possibilities you will get (one or the other, then one or the other, etc). Thus, if you prepare your city in order to have productions (or whatever is needed) ready when the quest arrives (which can then be either of two quests), then the next productions ready (because you know which two possibilities are up next), etc., you can still prep a bit and not be totally surprised.
You get this order:
Quest 1
Quest 2
Quest 3a or 3b
Quest 4a or 4b
Quest 5a or 5b
Quest 6a or 6b
Quest 7a or 7b
Quest 8a or 8b
Quest 9a or 9b
Quest 10a or 10b
And then back to Quest 1, Quest 2, etc., etc., etc. Rinse repeat into infinity.
So it depends on how you look at it (statistical or practical) but from a practical point of view, I don't see that as an insane high number in possible outcome.
But I think we can conclude that your hypothesis that it all follows a set order of a set algorithm and everyone gets the same order (which would then appear to be random) can be rejected. It's just RNG with a 50% chance on every quest option (except the first two, those are 100%).