Are you on Windows by any chance? What result do you get when you set “Detriangulate” to “No Polygons”? I can't seem to be able to reproduce this on Mac. There is an outstanding bug with similar circumstances that only surfaces on Windows, but I have only a single example of. The huge overhead of tracking this on Windows (need to have Windows dev setup and compare against another platform side-by-side) under the current development load has kept me from investigating it in absence of more failure cases.
As a side note, normals have nothing to do with Boolean's output. The winding of the polygons determine inside and outside but reversing polygons should only fix problems if you have made a mistake about the semantics of the operation. Most importantly, perturbation of the input should never be required or be a workaround. Please report failures to us through the bug database and preferably lock the inputs to the problematic boolean node in your submitted hip files.