To start with the easy answer.
Whos responsible.
Not the strata manager – they only act on the instructions of the owners. ( in the plural not the singular)
Not the council. The council is responsible for regulating the built environment. If the improvements contravene a council rule, they can require an owner to conform. Hedges and trees are a state government responsibility via the respective legislation.
Maybe the OC. Only to the extent where an issue is of general nuisance to the property. It seems that you are soLely affected by the neighbour, so you could be on your own here.
Generally properties are required to be fenced with a standard fence. I’d say a bamboo screen would not comply. However if the screen is entirely on the other property, short of court there is nothing you can do.
I think the action you are taking is correct.
good luck