Hi - Just installed the cookbook app - so far it is working well.
I have been making my own recipe book too - just storing the recipe in open recipe format, and a template for PicoCMS that formats it nicely. Advantage is it can be accessed without logging into Nextcloud - which is a pain when cooking with the phone and when you have two factor authentication on the web site.
https://open-recipe-format.readthedocs.io/en/latest/
The open recipe format is good as it is one of the few that separates the ingredient into a ingredient, a quantity and a unit. It also YAML - so is easy to write and is not as over the top as the XML formats.
The disadvantage is that nobody is using it - so you can’t just import recipes as easily 
Will have to see if I can write a converter
Anyway - interesting app. I am pretty surprised there is so little software around for recipes. I guess the foodies have been too busy taking over the tv stations and newspapers …