For X-Trans sensors (imgdata.idata.filters == 9), color pattern is contained in
imgdata.idata.xtrans (6x6 array, indexed by row%6,col%6, row and col are relative to visible area)
and in
imgdata.idata.xtrans_abs (same as above, but row/col are relative to full sensor)
Looks like rawpy incompleteness.
For X-Trans sensors (imgdata.idata.filters == 9), color pattern is contained in
imgdata.idata.xtrans (6x6 array, indexed by row%6,col%6, row and col are relative to visible area)
and in
imgdata.idata.xtrans_abs (same as above, but row/col are relative to full sensor)