I am sorry to hear Dumpling is having problems. I would say that the change of environment with you being on holiday and then back home again, will affect him and have stressed him. I had something similar with our Syrian who we left elsewhere for 10 day and apparently started getting very stressed by the last day. When we brought him home he was frantically bar chewing all the time and running round and round all the time - it was quite worrying and it took about another 2 weeks before he settled down. In the end he sort of got shocked out of it by a full cage clean. Ironical as normally a full cage clean stresses them out! I think he could still smell the scent of the previous house on the cage and once all scent of that was removed he settled a bit - I also started scatter feeding to distract him.
Having said all that - walking off balance sounds a bit worrying and robos are so small. It is possible he may have sustained some injury while you are away which may not be anyone's fault - he could have fallen in his cage and had an injury. The smaller eye may suggest this too (although to be honest it is surprising the things we notice when we haven't seen them for a while and the usually do navigate by scent and whiskers).
How long has he been back with you? You've already done a cage clean so that will also have thrown him a bit and I think the cautious navigating sounds to do with the fact that all his familiar scent has been removed from the cage after the clean, and on top of that he's had a change of environment again.
Robos often do take a while to decide where to nest if something has changed in their cage. If he's been like this for a while then I would suggest a vet check to see if he possibly has had some kind of injury. But if it's just a few days he's been back with you he may just be completely disorientated and needing time to settle again.
I changed our Robo's cage a few months back - moved his old bedding and nest across and left the layout the same and he still freaked out completely and sat and shook next to his wheel for 24 hours and then couldn't decide where to nest - he abandoned his old nest.
If he seems ok in himself otherwise, maybe just let him have time to settle in again - it can take two weeks so during that time don't do any cleaning or change things in his cage. You could scatter feed a bit as well as putting food in his bowl (a bit of each) and maybe hide the odd treat here and there in his cage for him to find, or add a treat parcel to distract him into destroying it
(Toilet roll with the ends turned down/in with something tasty inside).
It's a difficult call - because if it is stress and being disorientated then a visit to the vet will also stress him out. It may be best just to observe him and let him settle for a few days if it's all very recent. He may need to re-scent mark his cage, and find a new routine after the changes and cage clean and settle on a place to nest.
How to make the toilet roll food parcel is on this video
https://www.youtube.com/watch?v=NuPeyD6w-CI