Maldraxxus and Ardenweald were definitely not as up to date. It makes sense why Revendreth was done first the same reason Nazmir was done first for BFA, the first raid zone gets completed first.
If the IGN preview is to be believed Revendreth was actually fully complete, or something close to it, shortly around Blizzcon. They just showed Bastion because I guess it looks more afterlife-y?