Can China still be punished under UNCLOS in the Philippines v China case?

In my opinion, no they won't be punished and to some extent, they CANNOT be punished at this point. They started out with small violations that went unnoticed and have now made it to this but the thing to be noted here is that they now have more influence over the world and punishing them isn't as easy as it would've been years ago.

Indeed the tribunal ruled that China’s nine-dash line is essentially illegal and without basis under the 1982 UN Convention on the Law of the Sea (UNCLOS), which is at the core of modern maritime law and has been signed by over 160 nations (including China).

The treaty for instance grants exclusive economic zones (EEZs) to coastal nations extending 200 nautical miles from the shore baseline, giving them sole exploitation rights over all natural resources in that zone.

Hence even though they are doing a crime right in front of everyone, they won't be punished.