The fracture were on one of the thicker point of the main body, and crossfiber. We think that it were just a bad print, but we noticed that we have a uneven stress distribution, so we prefere to just redesign the part.
We usually don't do FEM analysis because it can't calculate fiber orientation, emptiness, printing defects and surface quality. It's almost useless. We just design the part thinking we're working with plywood, with fiber plane parallel to printing plate