When you "hover" over the various fields shown in the UI (at the top of the displayed info) calibre will show a tooltip that lists the field name.
So, when you hover over the Author info it displays
The lookup/search name is "authors". So all you would do is in the Kobo device driver configuration box where you supply the info for shelving just type in
authors without the leading # sign.
So I just tried with the following fields listed
#myshelves, #readstatus, series, #newsshelf, authors and all worked as expected. I doubt you will have that many fields; I just tend to experiment and try out rules as people as questions
