Hi. Yes it does take 10 days to 2 weeks. Even with all his old bedding he will need to learn new routines in a different cage and suss out where everything is and scent mark it. Before he feels less jittery. The problem with tweaking things or helping him in the early days is it can set back his settling in time. I wouldn't do anything to the ladder just yet. Moving things and changing things can stress them more. But adding the odd new thing can be accepted ok. So if you have a bendy stick bridge eg, then adding that next to the shelf somewhere (another way of getting down) might help. You might need to add more substrate in the area where you put the bendy stick bridge so it sits high enough to make a ramp.
It's all confidence. Once he's settled he'll be zipping up and down onto the shelf and might even enjoy sliding down the ladder.
If he didn't have a shelf before, then the house on the shelf may be a bit confusing, if he was used to having a house sat on the substrate. If you can also sneak in a cardboard hide under the shelf, when you put the bendy bridge in (eg a small tissue box or even another little house that's open underneath) then he may move in there. They tend to prefer nesting in a house that is open underneath and sat on the substrate so they can bury hoards under their nest and get cosy. It also helps a house stay cleaner and need cleaning less often.
I think it is the amount of space above that can scare them and it is quite a tall cage. For now I would try putting a blanket on top of the cage so it makes it darker above. That can help.
But no glue and cloth wouldn't be safe to stick on a ladder anyway. Some glue (Elmer's school glue) is safe for making toys etc but I don't think it would work well on a plastic ladder and cloth is definitely unsafe (for chewing and cloth threads can get wrapped around teeth and feet and cause circulation to get cut off).
One thing I sometimes use a ramp to a shelf is a cork tunnel - it's a bit taller than a bendy bridge so goes right up to the shelf and can be pushed down into the substrate a bit to hold it firm up against the shelf. It makes a kind of ramp to climb up the side of and also makes a tunnel. But they can be difficult to get hold of in the US possibly. They're usually sold for reptiles and can be far too big to fit a hamster cage.
Although you're used to handling him etc, I would leave him alone for 2 or 3 days now and not put your hand in the cage when he's awake - until he feels more at home. And don't clean anything or move things around for the next two weeks, so he can settle without set backs.
Just keep talking to him if you see him. And just put food and water out. Let him come to you when he's ready. Another thing that can help distract them from the change and scariness of it is scatter feeding. So put his food out as usual in his bowl but also scatter a little bit extra around the substrate. They enjoy foraging for it and forget to be scared momentarily
