"We have cooked them"
eng-kisw : Them does not indicate which class to use in kiswahili, could be people ("wa"), things ("vi"), or anything else, for all of which in english you would use them. So there should be an object, so that one can choose the right infix
edit: Of course "cooking them" referring to people would be kind of macabre obviously :D
I also was considering that the plural on several classes would be acceptable. I chose -ya- because "they" have used -ya- on previous examples and now it is not accepted. eish...I have reported. March '19.