Logical counterfactuals are key to Functional Decision Theory and last I heard still an unsolved problem. Unfortunately, I am still rather confused about what exactly we are trying to solve. The only concrete problem I know of in this space is the 5-and-10 problem. But as far as I know, this is solved by writing programs that immediately cause a paradox if they ever discover their output. So presumably there are some unsolved concrete problems that relate to logical counterfactuals?