GPO4 automatically pans the instruments and same for the depth.
But there are (at least) two common orchestral seating arrangements. Not everyone is going to like the provided panning. And to complicate things a bit, the doc refers to one arrangement; the supplied panning pretty much fits the other.
In some recent thread that I can no longer find, one of the Garritanites (DPDAN, maybe?) mentioned the seating arrangement actually used by GPO.
GPO's doc refers to a seating that, although common for many decades, is now becoming less common. Many orchestras are returning to a much older seating arrangement that has the placement of the 'celli and 2nd violins switched. There are probably other differences, too. (I thought this was true mostly of orchestra in the USA, but last evening I saw that the Russian National Orchestra uses the "2nd violins up front" configuration, too.)
In that case, there is also the configuration for the Vienna symphony orchestra. It has the first violins on the left front and the seconds violins on the right front, violoncelli in the left center, violas in the right center and contrabasses in the right bottom near the timpani.