I've suggested this before, but I haven't seen any movement in this direction.
Please make it possible, perhaps through an initial 'splash window' that appears when launching mp3tag, to open a default configuration or one of several optional configurations that include everything, not just the column setup in the 'grid' to the right of the tag panel. I mean everything--action groups, the customizable portion of the tag panel, export setups, tag mapping if used, directory list and the default directory, etc., etc. Everything.
Different tasks performed by different users for different purposes when managing a common music library or even individual libraries of the same or different file formats, likely requires different 'instances' of mp3tag, although they need not run simultaneously on the same machine. It wouild also be helpful to be able to exchange these config (zip) files to other users to ensure consistency among them.
Seems to me like the easiest way to do this is to offer a choice of confiigurations, previously saved by the user or users, when launching the application. Once the application is launched, a menu choice of all of the available configurations could then be used to close the current setup and launch a new one.