You are technically correct, those are unknown as well. I didn’t list them for two reasons:
- Every Onu-Matoran from Metru Nui/Mata Nui has a black torso except Taipu, Dosne, and Mamru. Taipu is still predominantly black, with both his feet and mask being black, and Mamru was the same prior to the rebuilding. This suggests to me that Black is the primary color for Onu-Matoran; those Onu-Matoran who don’t have black torsos have black feet and masks, so as to be predominantly black; and Mamru and Dosne replaced/recolored their masks during the rebuilding for unknown reasons, thus causing them to be exceptions.
- Every Matoran on Metru Nui had grey arms and legs.