Hi and welcome!
The LG is there already - because you followed good practice (as described in Dividing Roads) and reused the existing segment for the northbound part of the road rather than deleting it and creating new segments for both directions.
The intersection doesn’t need a JB - the simple turn restriction you’ve already placed will do the job. The circumstances where JBs are needed to prevent U-turns are H or # style intersections where there is a median segment. The intersection one block south (https://waze.com/en-AU/editor?env=row&lat=-33.90893&lon=151.20511&zoomLevel=20&segments=461226107) is now an H style, but even if U-turns weren’t allowed there we wouldn’t need to add a JB: Waze has heuristics to automatically prevent U-turns at H and # intersections that meet particular criteria (roads close to parallel, angles are reasonably close to right angles, median segment is 14m or shorter). So at that intersection Waze will not offer a U-turn. In theory we could add a JB at that intersection to allow a U-turn, but I don’t think there’s any particular routing benefit from doing that here.
These days we tend to be more active on our Discord server (see link in my sig block) than the forum, so please feel free to join there. We still do use the Discuss forum here (just not as much), though the wiki also doubles as the source of truth for our mapping standards, instructions and lots of other useful documents (Main Page),
Regards
Tim