The usual way to find the winding is to calculate the normal using the cross product of the first two edges and compare that with the face normal vector. Depending on if they point in the same direction, you can figure out what the winding order is.
Yes, without explicit normal info, the winding consistancy is just interpretation open.
Consider a mesh consisting of two planes, not connected, with one plane facing opposite than the other. Will you consider the winding broken? Or will you consider it a correct mesh?