Good question then:
When they say adjacent to a japanese controlled territory, they mean actually in the SZ, correct?
Meaning US ships can stop in SZ’s 16, 18, 24, 23 before it is at war?
“Adjacent” means touching, so yes, that means in the seazone that touches a japanese controlled territory. It does not mean seazone adjacent to the seazone that surrounds or touches a japanese territory.
So yes, 16, 18, 24, 23 are all ok for the US to hang out in.