I think the heuristic approach is not as bad as you think. Human crafters, and the current crafting techniques we have are pretty efficient. You don't need to explore the full graph of random states because the mod weights themselves are a representation of those states. As a human I can't think of any crafting item (alt and chaos spamming aside) where the probability isn't a simple to understand number. You think you can use something like modweight x currency cost (x some time modifier for acquisition and use of currency) for scoring. This is how craftofexile does it.
The more I think about this the more I feel you went really overkill on this. The complexity is several orderers of magnitude lower than what you claim. Like try crafting stuff on the emulator and see how easily you can narrow it down to usually 2 or 3 choices at most steps. There should be really easy heuristics to invalidate most branches. I've also used the COE simulator a ton and never had to model something that's on the order of 50+ states even.
