I went through several rounds and Google searches to figure this and couldn't find anything specific, so I'm going to pay this forward. I went through the entire game up to this point, only to realize something wasn't triggering right and I had to replay from the beginning since all of my saves came after the moment of truth.

Early on in the game, you *have* to go around and collect several Precurser artifacts to avoid being unable to progress later on near the end of the game. If you don't, your science team will never find the Daktak translation device and you won't be able to trade with them to get two game critical items. I believe you need to collect at least 7 artifacts before the second system collapses (Elantil), otherwise it's too late and you need to reload the game to an earlier point. This is just based on my own playthroughs, though, so I can't 100% confirm what leads to this, just that taking this extra step worked for me.

Something is wrong with how this game triggers you receiving vital information if you do some things to early or late, although this is the only game-breaking example I'm aware of.

How to avoid a game breaking bug? Dont play SC3 the whole game breaks everything.

I agree that this game is badly scripted.

I experienced a game-breaking script flaw which has wasted my entire playthrough.
When you buy your first Doog colony and you talk to it, it triggers a dialogue in which the Doogs give you an antimatter containment field that you will need much later.
HOWEVER! If you buy all of the 6 Doogs colonies before talking to them, it adds a new possible answer and if you choose THIS answer when you talk to the Doogs then it DOESN'T trigger the antimatter containment field dialogue!
I didn't notice it and played this damn game until the end when I needed the antimatter containment field only to realize that it was missing in my inventory, I was screwed...