Under the heading of "Military load," it says:
"2 13m Chuhatsu or 14m Daihatsu landing craft, 2 RIBs, 110 troops, 82t of cargo"
So, first of all, it lists either Chuhatsu or Daihatsu landing craft. But, it also lists "2 RIBs." RIB (or RHIB) is a modern craft, not WWII. It is a Rigid Inflatable Boat (or Rigid Hulled Inflatable Boat.)
So, it occurs to me that this might be referring (with alternate terminology) to the collapsible boats you have read about. It seems possible that--in addition to depth-proofed standard landing craft--these subs also carried a couple of some sort of "inflatable," or "collapsible," or "stowable" type of boat as well.
You said the translation was a bit garbled. Perhaps it is trying to indicate 2 different types of landing craft--one large/substantial and the other small/stowable?
Just a thought.