Birds for the most part, at least our companion birds, falcons, owls, eagle and other predators are of course excepted, have tunnel vision and no concept of glass & what windows are or that they are an effective barrier that prevents them from further escape.
You may want to re-think your training mode.....you might want to first establish your friendship with Johnny before continuing with other training...and...trying to train a previously un-trained bird while it's mate is present is often difficult at best, but since Johnny & baby may not yet be a real item, taking Johnny to a separate room, one he usually doesn't frequent usually gives you the advantage of being the only thing in the room he's familiar with, giving you the advantage of holding Johnny's undivided attention.....
Clipping is a controversial topic...it does limit the bird's ability to escape and is technically a temporary limitation, with the clipped feathers growing back in with the next molt.....having said that, there are those who will argue that a parront should take the extra time it takes to properly train the bird un-clipped or should have done further research before getting a first bird, let alone two birds.....
Personally, I would clip both birds, then establish a relationship with each bird separately and together at the same time...doing the individual training in a different room, then together, showing the same attention to each so that neither gets jealous.....then I would take each bird and let them beak/feel/touch each window so that they understand that there is glass there...the same with the walls Johnny has been flying into.....if you have ceiling fans, never have them turned on when your birds are out of their cage...never assume that they will see that the blades are turning and be able to avoid them. The period of time between clipping and their next molt should be plenty of time to establish a connection with both birds, do proper step-up & step-down training, no-bite training & any trick training you might be thinking about.....
The few times that I have clipped any of my birds, I did it myself, but your idea of having someone else do the clipping may be a good one as it will probably keep them from holding a grudge against you for their flight limitations.....
Good luck.....