I play videos on youtube-tv for my budgies, and many of the multi-hour "budgies in an aviary" videos, include cockateils in the same, VERY large and spacious aviary. I have Not seen any aviary with any other combination, only Budgies-Only, or Budgies & Tiels (with Lots of space).
Strongly recommend not mixing budgies with Any larger bird (other than 'Tiels), in its living space. My budgies have free range of my living area, including full access to Sunny's cage -- WHEN i am home with them. My Sunny is really calm and well-mannered, and when Jefferson-budgie oversteps boundaries, Sunny just Looks at me, like "REally???,: and kinda rolls-over on top of him.
BUT I would Not allow my budgies access to Sunny's cage if I were not home.
Budgies are well-known as beaky little brats occasionally, and your little Napoleons can get themselves killed taking on a larger-beaked bird.