Consider changing your topic title to "How to get a random list of full albums?" I've struggled with this too, and have essentially, given up trying.
you shouldn't need the full album modifier, ~limit should take care of it for you:
[Complete Album]==1 ~limit=500,-1,[Album],[Album Artist (auto)]
will return 500 randomly selected full albums, the problem then, is in the presentation.
If you use the default sorting in the "customise current view" dialogue, the tracks of those 500 albums are presented randomly, even though no ~sort=random has been specified.
If you open the customise dialogue, and remove the "media type" rule from the top of the sort list, then you get your albums grouped together, but always sorted by [album]. The same applies if you load the 'empty' sort preset.
It seems to me that the only way to get MC to pull random full albums, and keep the tracks from each album together, is to sort the results by album, which is rather defeatest.
The following will work well for you, if you don't have other media types in your library with matching [album] tags:
[media type]=audio [complete album]=1 [track #]==1 ~n=500 ~a
With the 'empty' sorting preset in customise current view, which will give you 500 albums sorted randomly, but, if you have any other media types in your library that have matching [album] tags, then these files will also be pulled into the results, which is why this approach is no good for me, as I end up with cover art files, and sometimes, video files, along with the audio, which is obviously, not desirable, and trying to use a second smartlist to filter out the unwanted [media types] destroys the random element of the original list.
-marko