Nice to know that others find it useful. It will be nice to get the Python version finished that can be passed on to Kovid and support additional features.
In terms of the Release Date you are looking for- I am not quite sure how you see this functioning? for instance:
- What field are you thinking of using for the "By Release Date" field? The current date field from the main Calibre GUI or something else?
- Did you see this as a top-level division or at some other level.
- If a top-level division, what would the next level be split by?
- what granularity were you looking for (year or something finer)