i rather think, you’ve found a bug here.
are you able to (re-)build cv2, locally ?
similar to this other issue, the function declaration here should be changed to:
CV_EXPORTS_W void matchLOGOS(const std::vector<KeyPoint>& keypoints1, const std::vector<KeyPoint>& keypoints2,
const std::vector<int>& nn1, const std::vector<int>& nn2,
CV_OUT std::vector<DMatch>& matches1to2);
after a rebuild, the resulting py signature should look like:
cv.xfeatures2d.matchLOGOS( keypoints1, keypoints2, nn1, nn2 [, matches1to2] ) -> result # returns matches now