I understand the confusion, but it's confusion one way or the other. The test dialog allows you to set the values of all of the available variables that would otherwise be set automatically according to the state of the tournament. Many of these values will differ from player to player (such as "finalTable"). When you run your formula to test for a set number of players ("Test All"), it has to use the same values for each player - what else could it do?
I see that I *could* allow you to place the number of players on the final table and have the software adjust "finalTable" accordingly when you press "Test All", but then that changes the whole "theme" of the dialog. I mean, it simply adds to the complexity of the dialog, and that dialog is frankly rather nasty as it is.