What does it mean for a throw to be forced in a multiplex pattern? What are the rules that you would be breaking if you failed to make the throw? The rule isn’t “no more than one object in the same hand at the same time” anymore.
For some patterns with duplexes — like 2, and 24, and , and (,2)(2,) — it seems like the rule could be that you can’t have more than two balls in one hand at a time. It’s okay to have up to two balls in one hand at any time, but if there’s a ball coming toward a hand that’s already holding two balls, you are forced to throw. You can choose to throw when there’s a ball coming toward a hand that’s only holding one ball, like you do in 24, but you don’t have to.
But that rule doesn’t work for 33. There is a time in that pattern where it’s not okay to catch two balls in the same hand.
I prefer to call it the specific activity of juggling. I don’t think uncategorized/unnamed activities (if there are still any) should be called that, because they’re not one specific activity; they’re a set of unspecified activities.