When is the ball past the fielder?

[CecilOne]

It looks like the OP question is more about geometry than rule. As described, the fielders are behind the "base line", but possibly closer to HP than 2nd base. The line between does not matter, but the distance from HP might.

The OP Q asks how to define "passes". A runner on 2nd is further from HP than F3 and F5, so "past" them. If F4 & F6 are playing inside the base line, (as if expecting a bunt), the runner on 2nd is "past" them. All that is based on distance from HP and it is geometrically possible to be outside the base line and be closer to HP than 2nd base.

I think that determines the rule application unless there is an interp which says anything about how close to the "passed" fielder the ball has to be.