Thank you again for your kind explanations. Deletions in my case are motivated by the following:
I'm ripping my CD collection; as we all know, CD files do not contain any meta data; the ripper tries to get that from dedicated web sites.
For classical music, though, that meta data to be found is more or less bad, often really bad; also, I want all the meta data to be within my file system, in order to be independent of what dedicated "music players" are able, or not, to find / filter...
Thus, I use the metadata from the web/ripper, and the CD leaflet data*, in order to (more or less manually) edit path and filename, and thus, whenever the (correct!) meta data is already in path or filename, I want to delete the meta data; ultimately, I then copy the metadata from the filename back to the "Artist" meta data field, in order for my music player to be able to display the track title (mainly).
*=It goes without saying that I prefer the web data IF it's more or less correct (or at least available to begin with), since for the leaflet data, I have to type it all myself; as alleged, classical-CD ripping is a nightmare...
So, in order to not get visually lost, I need to discard any meta data from the columns which I have already checked and processed, thus my need for quick deletion; as for quick copy-and-insert in mp3tag, I think I "got" this now, too, will share my observations after some practical use.
As for QUICK use of the tag pane, I'll have to do some macros, accessing the respective field*, then sending PageUp (in order to get to ), then sending control-s (thank you for your hint, my bad!), then sending Enter (in order to overcome the "Do you really want" dialog), together with the necessary pauses in-between.
*=Not all of them have an Alt-shortcut (which isn't available but once the tag pane has focus anyway), but gracefully, they are numbered: "Edit3", etc., with title = 3, artist 4, album 5, album artist 10 and composer 11
(I have to say that my files are .wav files, so my choice of tag tools is already severely reduced; then, I discovered a competing tool which allows for both tasks described in my first post above, so that's so much more convenient... but that tool - surprise! - does NOT also allow for editing the path and filename, and if you do that concurrently in some file manager, onto the files open in the tool, you'll create havoc; I tried and had to see what I got in the end, with that "work flow"...)
It's all a bit weird, I know, but classical music, in 2023, has become niche anyway...