Well done, it’s a fascinating topic - so much so I’ve somehow ended up buying three different revisions of the book
Just noting that D&R assert all rights over their code, formulas and calendar data and grant a license for personal use only.
I would propose you note this in both your packages in case someone accidentally believes the libraries can be used in commercial software without a specific license grant from D&R.
Thank you for your kind feedback and your suggestion!
I integrated the text that was used for the calcalc package (https://github.com/ferd/calcalc) into the README.md files of my pakages.