On many boards, Halma will display the number of moves in the minimal solution, so you can gauge your progress. If it says the minimal solution is “unknown,” it means just that— there is a minimal solution, but I don’t know it and didn’t have time to find it. If you find a wonderous solution to an “unknown” board, please let me know!
Even if there is a minimal solution given, that doesn’t necessarily mean you can’t do any better. Those values are just the lowest I could find in my research or discover on my own. If you find a better solution, please let me know!
See also: General --> References, Notes --> Contact.