It looks very nice and she has a lot to do in there and nice hides and tunnels. It could do with more bedding for digging and burrowing. So a few things I would suggest adjusting as hamsters really are diggers and burrowers and not very good at climbing and can fall off things and hurt themselves.
If you can have one end with deeper bedding at least, I'm sure she'd be more settled so she can dig and burrow. To achieve that you'd need to add cardboard, perspex or grass mats inside the bars at one end
Ideally, if it's deeper in the entire cage, there's less height with falling so not so many climbing things needed like the steps. The steps are very cute but hamsters do tend to fall off things, so if they have lots of deep substrate to land on and less far to fall it helps

I also try to fit any shelves or steps right up to the edge so there's no gap they can fall through or get a leg caught in. That isn't that easy to achieve in the plaza as the inside corners are curved! I had shelves and cut a little piece of the corners so they fitted.
For now if you just fill the base to the top with bedding it might help - even if it means raising some of the shelves higher up. Bits of bedding will fall out but it's not that bad. You could try with cardboard round the inside but she might chew it off. The cheapest option for the perspex panels are these - so you can just have one deeper end of bedding. £31 for the deep bedding panels at one end. You get to side pieces and an end piece 19cm tall. If you look at the second photo on the link it shows where they go
Personally I would think about doing that at the right hand end of the cage and keeping the shelf at the left hand end of the cage.
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Actually I've noticed a few people having the door opening upwards like you have

Not sure if that is by choice - I have the front panel the other way up and the door opening downwards

I think that's how it's meant to be but I'm curious as to people having it open upwards if there's a particular reason for it

I suppose it makes it easier for the hamster to climb out?