Allow Html pages for users with specific roles

You could save the HTML files in the theme with .php extensions and a short comment at the top naming each template, then either put the check-for-certain-role conditional within the php files and apply each template to a Page you create in wp-admin; or create a custom post type, apply each template to a CPT you create in wp-admin, and keep the which-role-can-read logic within the CPT registration.