Florian,
Yes, it's me again 
Have you thought about supporting the input of tag information (eg: csv files)? Basically, the order of the files in the folder by a specified sort could be the same order of the entries in the csv file.
Is this possible?
Yes, this is already possible via the converter Taglist-File - Tag 
As you might already know, you can export file and tag information with the powerful export function of Mp3tag. When you export tag information and keep the info at one line per file, you can import it afterwards with Taglist-File - Tag by specifying the format of one line in the taglist-file with a formatstring.
With best regards,
~ Florian
Thank you