Is that Advanced Fabbers cannot make Basic Factories. This may sound stupid, but TA had it like this for a reason; if you have nothing but advanced fabbers in an area, and you need a T2 structure instead of a T3 one (for example a Guardian instead of a Big Bertha), you could build a basic factory then basic fabber bots. I hope Advanced Fabbers in PA will have this capability. And yes, I know they weren't called fabbers in PA, but I'm just so used to it now.
I believe that this is intended because Uber want to separate T1 and T2 more, but I honestly believe that T2 engis should be able to build T1 buildings, albeit less effective at doing so than the equivalent metal in T1 engineers. This would allow to use them in emergencies like the one in the OP but also ensure that nobody has to to a T2 and spam T2 engineers to keep up a decent build force.
I think this is an alpha thing. It takes time to map all of those buttons so they will probably do it later on. I can't imagine this being consistent with the final product.
Well, I admit I don't want it to be like SupCom where any engineer could build anything of a lower tech level. I'm sure structures take up a butt-ton of memory in the Fabber's quantum memory storage or whatever, so you can only have so many blueprints. But I still want to be able to send an engineer somewhere and eventually have a fully operational base.
I think SupCom did it partially right in that T3 engineers were less efficient at contructing T1 structures than T1 engineers. Unfortunately, they were also less effective at contructing T2 and T3 structures. This resulted in people using hundreds of T1 engineers as their main build force until economy was no longer an issue and you could start mass-oproducing T3 engis and even support commanders. This coupled with the engineers' pathfinding made for some very messy bases. I believe that all engineers should be able to assist anything and T2 ones should be able to build T1 structures. But all engineers should be severely limited in their efficiency at building/assisting anything that is not "their" tech.