Using the Administration View tools for multi-language site creation
Here is a short how-to to create multi-language site pages. As You already know the best way to go is to create for each language a folder in your site like: /en/ /de/ One way I found out is easy to proceed is to create all pages and folders in only one language example "en" until all pages are done and the structure(folders) will not change. It is best to create all pages even if they don't have yet a clear content.
After that You can copy this whole /en folder to another folder like /de. Copy all files as new resources NOT as siblings (when selecting multiple folders this would be 'Copy all resources, even siblings' in the copy dialog).
Now You can use some interesting tools in Administration View, go to:
Administration->Content Tools and do these steps:
Select "Change Element Locale"
Here You can select the new created folder /de and change the locale from "English" to "German"
Go back and select "Merge Pages"
Here You will need to select as first folder /en and second folder /de
After this You will have all pages as siblings and all will work correctly.
You can as well add a new language by copying the content of one language-folder to a new one and follow the above steps. Just change the "Change Element Locale" of one the languages to the new language. Using "Merge Pages" only the new language will be merged and the old one will be ignored.