I don't know, I believe I've been able to expand the steppe once after the decision disappeared briefly. Unfortunately all of the options except for one then disappeared and didn't come back. It's very strange how it works, I feel like I'd need to actually look at the code for it to see what is going wrong (like the "Summon Fair Courtiers" decision just straight-up only fires the event once, there's no indication in the code that it was ever intended to give you three courtiers, so it's a mystery to me why the tooltip suggests you will get three).