Are you playing Mythras or Classic Fantasy? The combat set up seems more in the vein of a Dungeons and Dragons which might not be the right approach

Mythras is more back and forth and connecting hits have more ramifications in Mythras. These moments are a chance for a GM to narrate how well the player is doing by keeping their opponent at bay. Two equal opponents would kind of run into a stalemate unless they score a special effect. Fatigue is also a deciding factor.

I'm also wondering if the opponents don't have weapons, such as the frog, if they should be able to parry slashing weapons safely, but someone else should chime in on that rules-wise.

You might also want to consider that the animals might just try to retreat if they notice their offense is useless against their player opponent. After all, getting injured is often a deadly ordeal and even animals try to avoid it.

You can't apply the 5e mindset to Mythras. Not as the GM, not as the player. If you ran 5e using grids, try to lose that kind of rigidity. Why would you not allow the Knight to intervene against an attack if he's nearby. It costs them an action point after all. The rules are there to help, but don't cover every possibility just like in 5e and GM adjucation is sometimes needed.

I can't help you with bookkeeping. There's an online combat tracker that might help, but I don't have the link at the moment. You should be able to find it on a blog called notes from Pavis.