Going back to the MNOG animations, I noticed that Matoro offered Takua food to replenish his energy which was a Vuata Maca Tree fruit which indicated that food exist in the matoran universe.
“I noticed this one thing, please give me a detailed list of all instances of this thing” doesn’t really make for a good conversation topic. 90% of what you have asked in these topics can be answered by the most basic search on a Bionicle wiki like BioSector01, and asking other users to do what would be at the most a very minor inconvenience for you is a little rude.
In spite of that, however, I have done as you have requested.
I checked, and as far as I can tell Madu are just for throwing at people and wild animals like a civilized member of society. The unripe Madu Cabolo are also explosive for some reason, and smell awful when they explode, so I’m not sure it would be an edible fruit regardless of its ripeness.
Well Matoran eat by absorbing the energy from food by touch. So would anything really stop them from being able to consume Madu? Unless it’s a cultural thing.
Presumably the smell would, although if the Matoran is a stinky rotten no good irredeemable garbage member of society Ahkmou they might not be bothered