First of all, thanks for the kind words about the basic functionality of RSVPMaker.
RSVPMaker provides a number of dynamic blocks as a more user friendly alternative to shortcodes. Is the issue that Elementor doesn’t support Gutenberg blocks, and that’s why you’re using shortcodes.
The challenge with your request is that I have never been an Elementor user. Instead, I’ve been going down the path of maximizing support for Gutenberg blocks, including full site editing for block themes. I know a lot of people use and love Elementor, but for me it just adds another layer of complexity.
But that’s just personal preference. I’d be happy to invest some time in learning to create Elementor widgets for RSVPMaker if you (or some other fan of that software) wanted to sponsor the development for a fee TBD. Or, in the spirit of open source, someone provided the necessary code, I’d be happy to incorporate it.
Otherwise, I’m sorry, but I don’t think I can make Elementor support a priority.