Both the Tsi'hu and the Omnimek are using the same Skeleton it looks like, that is probably why you see similarities with the kneecaps. If you take another look the Shoulders are just as similar. Heck the Tsi-hu body even has a similar form to the Omnimek. It probably makes it easier of development of the characters across board.
I am liking the look of the Tsi-hu but the armor looks to be metallic. When they transform from humanoid to beast, is the armor poly-mimetic in that it shapes and forms along with the Tsi-hu? The hook looks good too and I am also wondering the propulsion means of how it grabs a humanoid. Is there a magic behind the propulsion or a motor. If motor how does it propel the multiple chains that it has? Is there a targeting system for the chains? does only one of the chains have the hook? If so what do the others do for purpose?