Probably more than normal clumsiness as he is clipped
As I said before- you and your mum really need to sit down and talk about this stuff and get on the same page s to how to provide and care for this bird- the constant perch and cage changes and power struggles between you as to where things are put in Cosmo's home are not helping your bird nor is any of this daily changing things about fair to him.
You need to stop putting things in, moving them in a few hours, removing them as soon as the other one is out of the room then the other one putting it back in a different spot etc- your bird will have no clue where he can sit, how to safely navigate the cage nor will he feel safe in his cage (his home) if you are constantly doing this stuff you have been posting about.