It seems that in de IDE debug window you can only see the variables from the active page.
You can set a break point in the B4XMainPage just before the call to the other page so you can check the values up to that point.
The public variables from the B4XMainPage you can check with a log entry set in the right place of the active page using the access you described.
These are the possibilities available at the moment.
Maybe you can write a wish for an upgrade of the IDE environment...