Also added name The Letter A as place=locality at the junction of George Downes Drive and Walkers Ridge Road.

Hi
I am not very familiar with mapping buildings. The osm inspector (areas) picked up the problems because you used a multipolygon relation which appears ok now .
I expect that an easier way to map complex buildings is to use a type=building instead of type=multipolygon. I think the way to construct the various parts of the building allows for overlapping ways. You need one way encompassing the whole building and then all the parts fit inside, each with their own individual tags. All of these polygons, including the encompassing one and any holes (inner) go in as members of the relation.
I have not made myself familiar with building relations so I could be a bit mistaken.
But I think using multipolygon relations for mapping complex buildings is fine too.
I guess each is done with a differing method.
Which method you use is probably just a personal preference I guess and one may be more suitable certain types of building.

osm.wiki/Relation:multipolygon

Hi
Multipolygons cannot be constructed as you have done.
https://tools.geofabrik.de/osmi/?view=areas&lon=152.88689&lat=-27.37132&zoom=19
You need to read up on multipolygon relation validity.

Should the name be PhotoGear instead as is depicted on the web page?

Found very recent comment on Massage Therapies Enishi so have put them back. Now think the estate agent, Power and Henderson have gone. Unit number seem ok too, so will leave at that.

I found another business, the Makaveli Italian restaurant, to claim unit 2, so Waves & Fades must occupy the next space which was the Enishi massage parlour, https://www.enishi.com.au
The website for Enishi seems out of date so I have removed them.

I have used the websites of the businesses beneath Glen Towers to map them (from afar).
I have assumed Waves & Fades hairdresser has taken the spot previously occupied by the TAQIZA restaurant which has moved to Hall St.
The unit numbers don't appear in expected order but I have used the info on their web sites.

Hi
The website as tagged is a barber shop with a different phone number. Hours suggest a brothel. Do you need to add more than one business here on different nodes.

Hi, are the opening hours correct?
Mo-Su 1:00-18:00 means 1am to 6pm.
If you instead wanted 1pm-6pm then 13:00-18:00 is entered.

I noticed the article mentions it...
https://www.smh.com.au/national/nsw/column-8-whats-in-a-name-20141013-115atv.html
There is an 'A' on top of the big tower at the National Parks office on the road junction. The Letter At is signed on George Downes Drive at both sides of locality.
I think it should be tagged next to the road junction on a node as a locality named "The Letter A" instead of a landuse=farmland

Hi, there is a problem with you boundary relation.
https://tools.geofabrik.de/osmi/?view=areas&lon=153.02430&lat=-27.40540&zoom=15
Schools normally have simpler mapping with an amenity=school tag on the boundary only serving as the container for all within. If you must use a relation, i.e. where campuses are in more than one property, a multipolygon type is probably more suitable.

...fixed

Hi
you are expected to correct all the trails you have named with upper case to title case.
osm.wiki/Names
There are no regional rules to do other than title case.

I updated the multipolygon

Hi, osmi has identified problems with the wetland multipolygon
https://tools.geofabrik.de/osmi/?view=areas&lon=145.79944&lat=-16.96466&zoom=13
I suggest you use the Josm editor for multipolygons

….and is clearly visible on Esri imagery

There is no evidence of a hotel here.

The mapping updates the osm database immediately but the rendering of the map takes longer, with the standard layer sometimes taking a few minutes to a day or so. Refreshing or clearing the cache on your browser may help (control+r for me and control+ f5 for some). Other upstream caches may be the cause delays - my phone takes a very long time even after clearing the cache.
Another way to see the latest is to copy the url from your browser and paste in a tor browser which is unlikely to be caching part of the map tiles for your area.

I think it is all mapped fine, thanks