I've just rigged and exported a simple geometric figure. After loading it in SFM everything seems fine, except I found out that the compiler added a new bone (rootTransform) which has a completely different orientation than my custom-made bones, i.e. some axis are flipped and also slightly inclined.
It's not a huge issue in this case, but I hate when bones in SFM have all different directions, and for more complex models I'll definitely want all of them to have the same orientation.
Also: it appears parenting bones in Blender may affect their axis orientation in SFM. Is that normal? Anything I can do to prevent that?