@BR -- I finally have my excuse, I guess...
@ Alexander, I have for a while wanted to be able to store the original filename in a custom column (for reasons explained
HERE).
But... I was always too lazy.
One way would be to patch calibre, to add in a feature that allows keeping the file contents metadata and overriding it with the filename regex (and also enabling custom columns in the from_filename metadata). The other way would be to add it via a script, possibly via calibre-debug, possibly via bash.
I will have to see sometime soon, if I can bash something together.