They did each intercept at least one ship loaded with Army personnel & supplies bound for the Philippines. I ran across the mention of this in Goldberg's book about the Sub Boats.
Malama was one, she is listed as a Hokoku Maru victim in the summary attached to the Ondina battle report. So I would assume that list includes all her wartime victims. Aikoku picked up Malama's survivors, so that shows the 2 were operating together from early on.
Aikoku bagged another Sub Boat about the same time in the same area, but if any non-subboats were also victims the book don't say.
So there went 2 ship loads of aid to US Forces in Philippines, but whether or not these ships would'a gotten thru the rest of the Japanese blockade is doubtful.