Hi Stevie
It helps to say their name over and over again softly. Don't imitate the buzzing or hissing sound they make as that is aggression they show to each other. It's a good thing you are trying to speak to them gently even when they are aggressive.
You could try a feather toy like the type you get for cats and have them chase it through the bars of the cage. So that they associate playing with you.
If you notice the female won't let you near her or her territory try offering her something she can't refuse when she does something good. So that she understands you are the person with the good stuff and not to be mean to you.
I usually hold the treats near the bars so they have to run up to me. She may try to swat the treat at first but hold it there until she realises its not dangerous.
Also the shhhh noise you make will upset them more as that is the noise they make when picking a fight. I learnt that the hard way. If you need them to back up without scaring them blow at them slowly.
If you have trouble getting her in a tent try some thick winter gloves. I know this seems strange but I find the gloves are good for new gliders so they don't associate hands with snatching them from their homes and dropping them in a tent. Eventually when they like you they will crawl out themselves and you won't need the gloves anymore.
Make sure the gloves are thick like ski gloves or thermal. This is so when they bite they won't draw blood. They are scared of you at the moment and if they end up biting you hard you're going to feel the same about them.
Another thing you can try is a large hamster ball so that they can roll around and see you while playing even if your busy. But remember put some tape to secure the balls as they can bash them open whilst knocking into things.
I hope all this helps. I'll let you know if I think of anything else. But don't give up as they all eventually bond. Each glider is individual our worst one is happy being picked up, jumping on us, playing but unfortunately won't stop pulling on my hair and digging into my scalp. It's a habit I've not yet been able to break.