From what I've read, it seems that they often do walk around on their hind legs. On Wikipedia, it says, " The less experienced cat has difficulty standing on its hind legs while the older cat is able to do so." The website yokai.com seems to agree, saying that they are "most likely seen walking around on their hind legs and speaking human languages." So, to answer your question, it seems that nekomata often did engage in human acts, such as walking on two legs. Also, in this image![enter image description here]( a nekomata, it is shown wearing human clothes and playing a shamisen.