I'm a bit confused now
You mentioned a pair of robos. Is it the Syrian who is escaping from a cage with 1cm bars? There is no way a syrian could get through 1cm bars - so either there are some bigger gaps somewhere, or she is opening the door (assuming no holes chewed in the base) - but then you'd find the door open. Very mysterious.
I think a detolf would be a good idea. Yes it's narrower but also longer and lots of scope for enrichment. If she's a chewer though, it does have bars inside and wood ends.
For the robos - I have a 100 cm cage for our robo (actually the Savic plaza - I tied 4" height cardboard round the inside to reduce the height by having deeper bedding). It's just the right size for him. If it's a pair I would go with an 80 x 50 cage though, like the Savic Mickey 2XL (which our last robot was in) as too much space could make them fall out.
If you're an experienced owner you may want to try and keep them as a pair but the slightest sign of fighting and they'd need separating. I very much preferred having a front opening door with a robo, for interaction.
Shame your Savic Plaza arrived broken - I had one arrive with a broken plastic bit. This used to happen a lot with zooplus cages too! While it does seem a bit flimsy putting it together, I find it's fine once constructed and it has it's pros and cons - I prefer the solid cage tops ideally (especially for lifting the top off in one piece) but the plaza has that lovely big front door and no gaps at the corners - plus the whole roof can be used to attach things to.
My favourite 80 x 50 cage is the savic mickey 2xl. It's the same as the hamster heaven but no tube holes and has narrow 7mm bar spacing. It's also a good low ish height for dwarf hamsters and has the same flat roof and big front opening door.
Had mine for years and it's very solid and well made. The base got cracked when we moved house but I found a replacement base. The bars are very strong and well made.
I could never get on with top access with tank style cages, but a longer cage like the detolf or a lower cage like the maxi duna multy, might be ok as you can kind of put your arm in at an angle rather than directly from above.
The maxi duna multy is a funny beast. I think it's limited by height for a Syrian - if fitting a platform in and a wheel - but still a good cage for a Syrian. And a good size for a single robo. But I prefer front access for a robo as they get freaked out so easily.