If it were possible to consider the first, say, three values of a tag in a certain column instead of all of them, it might be possible to display more efficient / accurate results, especially if you have multiple tag values ordered by frequency/weighting but don't need all of them.
I came up with this idea after fetching album descriptors from RYM, but wasn't entirely happy with either all or just the first tag (per Virtual Tag with $First function) being used for display. The RYM descriptors are ordered by frequency, starting with the most frequent. I think a function like this could give the user more control while filtering some tags that have multiple values.