Poland Rudnik nad Sanem (podkarpackie) podkarpackie
Trzewik is working on the new small expansion (or the promo set) which will contain new cards, but propably much more less then in the classic Empire Pack. It will contain basic cards which uses Aztecs mechanics and propably some single-player cards. The first shown card from this expanion is Tempel Construction Site and allow us to do an Action: Spend 1 wood, 1 stone and 1 worder to gain 3 VP and may be activated twice.
It wasn't been called typical expansion or Empire Pack, that why I think it's an optional content besides standard format.
They did give misprinted 51st State card on their store for minimum price, so maybe they will? But usually companies just fix inconsistencies in new print runs and this is the pain of early adoption. I've suffered it a lot.
Any progress being made on fixing the base game errata?
I wasn't aware that it needed any. I've played mine a dozen times and have never come across a misprinted card or unclear rule.
I think the initial print had problems with wording. They fixed it in future prints, like mine. Errata paste-overs are available here so you may want to check it out, just in case you got a first print.