ZoneSwitch rules work as relationship groups. If you have one zone set to stop playback in one or more zones, make sure all those other zones in the relationship do likewise. So if Audio 1 stops playback in Audio 2, Audio 2 must do likewise to Audio 1.
Otherwise, there is no relationship, so playback would not be stopped in other zones.
When you say "without stopping playback" "in the current zone", what do you mean by "current zone"? The one that the UI has focus, and is the target of the media controls? If so, this is a problem if you have Audio 1 and 2 related to each other, and Audio 1 is playing, and you're targeting Audio 2 (or, as you say, "if I'm in Audio 2"). Your ZoneSwitch rules will then by definition stop playback in the other zone (Audio 1), if you've defined them to do so.