It would be a nice addition to do this:
So:
Mp3tag.exe /wss:"<Name of script>" /fp:"<full-qualified path to directory>"
Will load the files from the folder and run the script as normal. Giving the usual options.
Mp3tag.exe /wss:"<Name of script>" /fn:"<full-qualified file name>"
Starts Mp3tag with the specified audio file using the directory of the file as working directory using the web source script.
To add to these, Command Line Interface – Mp3tag Documentation
I have my problems to imagine how my workflow would look like if this feature got implemented - perhaps you can help a little.
In general: would MP3tag open the GUI or run silently?
So, taking
like that would leave me with the question: which files would be treated by that wss?
Would I have to supply a folder or at least a single file as well or would the standard folder be used?
What happens if that folder does not only contain a single album but is e.g. my folder for podcasts (which would probably not create a lot of hits with the most prominent wss). What happens if only one file from that folder leads to a hit and all the others would be overwritten with the wrong data if I took that suggestion? (I think I would have to abort that wss-call and start from scratch with just one file selected ...)
What happens if no file is loaded? (Because I always start in an empty folder / because I forgot to include the filename in the command line.)
I assume that all further wss-steps like selection of the issue, arrangement of files in the correct order would then be carried out as usual with user-interaction (which in a way answers the question whether MP3tag would run silently), yet, if the idea was to run the wss sort of automatically, it would have been interesting to see how the correct data would be assigned.
Perhaps you could elaborate your idea a little.
Just as side note: it has been requested some years ago to run actions via command line, see here
(and there are more with this idea)
Yes, the file or folder would need to be supplied along with the web source script.
So:
Mp3tag.exe /wss:"<Name of script>" /fp:"<full-qualified path to directory>"
Will load the files from the folder and run the script as normal. Giving the usual options.
Mp3tag.exe /wss:"<Name of script>" /fn:"<full-qualified file name>"
Starts Mp3tag with the specified audio file using the directory of the file as working directory using the web source script.
It would just be a quick way to run them inside foobar2000 using the foo_run plug in.
Yes this would be a nice addition. Per example i will use it in my python scripts.
My vote would be for it to run silently and would be okay with risk of script user error when specifying an entire folder. But you could first handle single file case, then hopefully take up the actions script ability I suggested ten years ago from the link you quoted. Thank you for your program!
Thank you 
There could be a /silent switch in there also.
The undo function in mp3tag could undo those changes.
Possibly another CLI command.
Mp3tag.exe /undo
or
Mp3tag.exe /undolast
Something along those lines.
The Silent switch would need to be used with direct scripts. But to start off with just having the ability to directly run a script would be a good start without getting too far ahead of ourselves.
While you get all excited about further functions that might be triggered in the command line, I would like to draw your attention to this thread:
I've written an AHK script to do this.