Sublime Text - Apply Syntax - Rules for flask Jinja2 templates and Elastic Beanstalk Extensions

ApplySyntax.sublime-settings

{
    // If you want exceptions reraised so you can see them in the console, change this to true.
    "reraise_exceptions": false,

    // If you want to have a syntax applied when new files are created, set new_file_syntax to the name of the syntax to use.
    // The format is exactly the same as "syntax" in the rules below. For example, if you want to have a new file use
    // JavaScript syntax, set new_file_syntax to 'JavaScript'.
    "new_file_syntax": false,

    // Auto add extensions to language settings file in User folder.
    // Do not manually remove "apply_syntax_extensions" from the settings file.
    // "extenstions" are ignored by "match": "all" setting.
    "add_exts_to_lang_settings": true,

    // Control level of logging in the console.
    // (true|false|"verbose")
    "debug": false,

    // Put your custom syntax rules here:
    "syntaxes": [
            {
                // I put XML first because of files like *.tmLanguage. It is unlikely
                // that this rule will result in a false positive, meaning if it
                // matches, you probably want the XML syntax
                "syntax": "YAML/YAML",
                "rules": [
                    {"file_path": ".*\\/\\.ebextensions\\/.*\\.config"}
                ]
            },
            {
                "syntax": "Jinja2/Syntaxes/HTML (Jinja Templates)",
                "rules": [
                    {"file_path": ".*\\/templates\\/.*\\.html"}
                ]
            }
    ]
}

The trick in this file is the name of the Jinja2 syntax! It was hard to find: to find Jinja2/Syntaxes/HTML (Jinja Templates) you need to change the .tmPackage into a .zip file, extracting contents, then find the path!