thanks for asking.

In Remote Buddy, Actions can claim some button exclusively - which 
is, what the Virtual Keyboard does to allow users to

a) map every button for the virtual keyboard (i.e. cursor keys) while 
the Virtual Keyboard is not shown.

and at the same time

b) when the Virtual Keyboard is active, be able to navigate it and 
press keys - "A" in particular is assigned to press the selected key 
(surrounded by a blue border).

So, when the Virtual Keyboard is active, the navigation cross on top 
of the remote and its A and B buttons are overridden by it. The rest 
of the buttons can still be mapped however you want to map them, though.

By default, the left mouse button on the Wiimote is assigned to the 
"-" button next to the "Home" button on the Wiimote. So, if you press 
that button while hovering over a key, will press it.

That of course assumes, you did not change the mapping of that button 
in the global mapping table (=> you can reset it to defaults with one 
click in Preferences >Hardware > Ninte... > Globla mapping).

Hope that helps.

Best regards, 
Felix