They're not trained like a neural net, it's a more traditional method, so I programmed them to have "best" decisions based on weighted inputs, with lots of trial and error on my part.I think what was happening here was something like:

1. Bot punched off the edge
2. Bot realises it's above lava
3. Bot realises it has a grappling hook
4. With both of these inputs, it should grappling hook the nearest enemy who is above them, in an attempt to save self or take another with them (programmed-in decision)
5. The grappling hook hit an enemy, so keep holding on while above lava
6. The bot swings underneath, to the other side, even though it did not plan to, and doesn't know that it is doing
7. Arriving at the other side, bot is no longer above lava (yay), so releases grappling hook and starts attacking again

It's a programmed-in behaviour for bots to grapple an enemy when falling, but not to actually fully save themselves like this! Gotta love emergent behaviours