I had a deeper look into the forms and registry packages and I'm starting to see more of the issues.
I like the idea of creating a form from a registry object as that would save a lot of duplicate work when it comes to supporting different data formats and one other important issue in my opinion is custom HTML attributes. Rather than have fixed attributes I like the idea of being able to add any attributes you want on any field as these days with HTML5 data attributes and such there's no saying what they might be called.
Could you send me a link to the work you've already done regarding using the registry package? As long as there's no objections I'm going to start with that first as the ability to create forms from JSON, YAML etc. is one of the main priorities for my own project.
I'm excited as I've been making a living out of Joomla since 2007 so the idea of giving something back is pretty awesome lol.