Whoa, I'm surprised that you've managed to do almost any ecosystem interactions! I've done almost no work on those systems. In particular, I want the basic follow-hunt-eat loop for a creature to work, and it's still pretty far off using the out-of-the-box pieces.
I like the healing idea. Work on that is going to be a ways off because I'm currently aimed more at use-in-neurobiology-classrooms than the fishtank aspect due to increased interest for remote neurobiology activities in the wake of the pandemic. But I'll get there someday! 🤞
Harpoons are still in development; I haven't been able to release an update with them yet since I injured my wrist and have had to take it easy re: computers. If you have CL installed using the Itch client, it should update the game & preserve your creatures seamlessly. Otherwise you'll have to transfer the saved creature files over manually to the new version you download; they're in internal\creatures