If it's that hard to get up and running, you can do the same thing in Divi in a few hours. See https://67biltmore.com. Built that in Divi with Open Menu for the restaurant menu system. Some light custom coding, but overall no reason to back yourself into a fixed restaurant theme that needs all those additional plugins and all that heavy lifting. I specialize in restaurant themes and wouldn't use a theme like Rosa 2 - especially with all the issues you've described.