I think my concern about this section is a little more serious than the way you described it in your summary of my remarks. So the first one, proposed paragraph 34.(1)(a), the person has to “believe on reasonable grounds that force is being used against them”, does sound a bit like the first element. I think it's important that it's wrongful force that's being used against the person that is the first element.
One might have thought that a court would be ready to read that in, except for the fact that the court is specifically directed by proposed paragraph 34.(2)(h) to treat the defender's knowledge of the lawfulness of the force as a mere factor, which seems to open up the possibility that this section could justify resistance to a lawful application of force. I don't think this can possibly be the correct way to think about self-defence.
On the first one, that would be my comment. On the second one, the proposed section says that the act has to be committed for the purpose of defending oneself. I agree with that, but I think it should also be necessary not just for the purpose of, but also necessary to that purpose. So one might commit force for the purpose of protecting oneself when one had other alternatives, such as calling the police, or closing the car door, perhaps, or using some means of protecting oneself that was less intrusive--