Check your building’s by-laws to see if they have the standard clause (or variation thereof) that says: “The owners corporation is responsible for cleaning regularly all exterior surfaces of glass in windows and doors that cannot be accessed by the owner or occupier of the lot safely or at all.”
If it’s there, write to the strata manager, building manager or committee and politely ask why the windows haven’t been cleaned.
You could also ask if the fly screens are original.