"In addition, while it is not about creating a new system but developing the existing systemů"
I've been told that the phrase: "it is about" as in the above context is not correct English. Could you suggest a better expression? (Perhaps: The matter at hand? The subject under discussion? )
PS We are assuming of course that there is an elided finite verb after the subordinate clause. If not, the 'while' is out of place (not just 'in the wrong place', but not doing the job of a subordinating conjunction).