I mapped and visualized a number of raiding party spawn locations, and found that raiding parties can spawn outside of ticking chunks (4-chunk sim distance), especially in the negative-x/negative-z direction from the village.  Positive-x/positive-z raiding parties appear to spawn on an arc that almost entirely keeps them "in-bounds," but negative-x and negative-z parties appear to clamp to lines parallel to the x and z axes (best represented in the attached visual).