LOL at thru the bars...its unlikely they would try but NOT impossible for the deed to be done if the connection is made. What needs to be really the consideration here is they are still in a stimulation mode and thats enough for marley to decide to want to lay eggs fertile or not.
and of course screeching will be a jealous issue where one is out and being able to be or get into mischief while the other has to be a onlooker...and a cover wouldnt make any difference as they can still call their frustrations out to each other...and MAY make them all the more determined to screech lol...its gonna be one of those times when you will have to figure out a solution but at least they are now separated...so there wont be any babies however,,,as long as visiting continues with each other the stimulation is stilll going onnnn giggle.
you may have to put them in completely different rooms and let the one that is in a different room get adjusted for out time flying to keep them separated and not visit...
and btw it can take a few months for them to come back to normal and not be in a breeding state of mind...you will know this when you see her cere go back to normal...the males cere can even become much deeper and brighter when in that frame of mind...
Cappys got realllly deep in color when he did and he doesnt have a female so you see ...its not just a female thing here and WOW just ask pepper or kk what i went thru on that being territorial of his cage geeeeeeeeeeesh...
once i figured out what the heck was his issue i realized i missed all the signs leading up to it...for him being a single male bird he got rather amorous overly so with a couple of different toys he had...i couldnt even go near them OUTSIDE the cage never mind IN it...
and this bird was NEVER a lunging lunatic out for blood till he came into breeding status...so he and i had a little lesson on who was ALPA because i was gonna feed water clean or what ever in that cage without him ready to have me for lunch giggle...
i decided or rather we decided the only spot in that cage i would allow him to be in charge of was when he was on his swing...any other area was equal domain...lol...
and let me tell you these lil birds can be VERY determined as it took a entire afternoon NON STOP of proving just who was ALPA and re-establishing the pecking order in the right way.
thing is now...i know...he wont ever forget THAT afternoon because of how he STILL behaves now an has that look every time of respect when i mess with his errrrm favorite errrm toys etc....sort of not tormenting but keeping that afternoons lessons fresh in his mind sort of thing...there is a mutual respect now...he knows he has to share his toys but its usually a short time and he has total command of his swing when on it lol

and his cage is not totally HIS domain...its MINE too.
note the difference in cere color in these pics...you will see what i mean


gawd i just lost power then couldnt log in geeeeeesh