Factorio is a game that requires SIGNIFICANT amounts of thinking ahead, often requiring investments into things that won't pay off until much later and which might even significantly hamper initial development. Building a main bus vs spaghetti belts is one of the obvious examples here.
Humans with a little bit of experience playing factorio know that while building 1 item/s of some new resource is good, the game is about eventually building thousands of the new item. Until the LLM learns not to be short term minded it will probably build itself into a corner very quickly.
It is kind of amazing that these models manage to figure out a strategy at all, considering the game is not in their training set. That said, the current research goals are not very good IMO. Building the largest possible base has the predictable result of the AI building a humongous belt loop covering much of the map. A much better target would be the "standard" goal of SPM.
I think 99% of Factorio could be "solved" with GOFAI algorithms from the 80s and enough processing power. Set up a goal like 10k SPM and then work backwards towards how many of each resource you need, then recursively figure out fastest way to set up the production for each subresource using standard optimization algorithms from OR. No LLMs needed.