That's a good question.
The QRecall Activity window is independent of the QRecall application. So, technically, it doesn't belong to the QRecall application and isn't affected by its window order. Hiding or quitting the QRecall application won't hide or close the QRecall Activity window either.
Having said that, I'll look into the possibility of hooking the "Bring All to Front" command and bring the QRecall Activity window to the front at the same time.
You can always bring the activity monitor to the front by using the Window > Activity Monitor > QRecall Activity (Command+0) command.