Is it 100% buckwheat? Also is it going to be malted buckwheat or raw?
When we experimented with a buckwheat whiskey it was only about 1/3 of our mash, and the rest was malt so our problems may be a bit different. We treated the buckwheat same as we would corn and that seemed to work well.
But also, this….Optimisation of a Mashing Program for 100% Malted Buckwheat : https://onlinelibrary.wiley.com/doi/epdf/10.1002/j.2050-0416.2006.tb00708.x