Results of studies of this sort show that most of Chantek's signs came to mean the normal adult meanings. Chantek overgeneralized in interesting ways, too. Then he started using bad, and dirty changed its meaning to be more like the real meaning. There are several other examples of overgeneralization. Chantek did this often.
Deception is also an important part of language development.
Chantek made about three deceptions per week. There are some interesting examples in the paper. Though he wasn't taught to do it, sometimes Chantek would sign with his feet. This is evidence for a mental representation of an image of signs. Chantek had a strong left hand bias in signing.