Sup supsupsup,
The importing sounds like an image export issue
- The exports might not all be of identical size: Trim Whitespace during the PS script will do this - turn off trim whitespace and manually crop to the tightest possible size before exporting via script.
Reason: Zeroing the images will have everything centered in Spine meaning the images will have appeared to shift pixels if any are smaller or larger than each other. Disabling Trim Whitespace should ensure no dimension changes.
Also an improved method for placing a sequence
Instead of dragging images onto the stage, create a bone first and drag the images onto the bone in the tree. This will automatically center all images onto that bone keeping things organized and aligned in one action.