Just a wishlist request: In the file list, certain columns can be displayed (e.g. Name, Size, Type, Date Modified,...) when selected by right clicking the column header. Could the "Rating" column be added? This would make it easier to see per folder how many tracks have a star rating, rather than having to select them 1 by 1 and checking the value in the Tag 2 section. Thanks!
I also received an email about this bug report, however, I have not generated it, maybe some automatic action done by bugs.kde.org because of inactivity? Concerning your feature request: It is possible that I extend the selection of frames to be included in the file list columns from "standard tags" (as it is now) to "unified tags" (which would also include "Rating"). However, "Rating" would be a bit more complicated because it uses a custom editor. So this will probably not be part of the next release. If you just want to know which files have a rating frame, you could add a custom filter (menu "Tools/Filter") with the expression `%{rating} not equals ""`.