Hi, so one governing principle of SongKong is we always add the data to the files themselves so that the song files metadata is independent of the tool used to modify them, and the file location. This is different to tools such as iTunes that store some data such as playcounts, ratings and artwork in the iTunes library so they are not transferable.
We additionally allow artwork to be stored in the folder as well because this is used when browsing your music by folder, whether on a computer or with a music player but the primary artwork should be the embedded artwork.
Now to your problem, if you think the artist artwork is wrong how wrong do you mean, the wrong person or wrong picture of person. If wrong person then that means in your mind that the album artist is probably wrong as well and you need to change a setting, can you give me some examples.
Are these Classical albums ?
You could either run in Preview mode first and in report use Browse/Browse By Artist to check for any album artist artwork you think is wrong and then if found make adjustments and configure to Save album artist to artists folder in filesystem to Yes, but do not overwrite existing artwork in folder
You make a good point that Manual Edit only supports cover art not artist art at the moment, I should add that.