I must admit, I don't fully understand admin boundaries/levels. I just used this value (6) based on other nearby islands,as being tagged as a boundary but with no level was flagged as an error.

After looking into it, I found a map (https://portal.spatial.nsw.gov.au/portal/home/webmap/viewer.html?useExisting=1&layers=3e1edb6861524b5490c74db81e42433a) that shows Wasp Island as separate to the LGA of the mainland. Does that mean it's unincorporated, and if so, is level 6 then correct?