For HTML and JS, you should try using
${properties.customHTML @ context='html'} <!--/* Use this in case you want to output HTML - Removes markup that may contain XSS risks */-->
${properties.cusomJS @ context='scriptString'} <!--/* Applies JavaScript string escaping */-->
HTML Template Language Specification - https://github.com/adobe/htl-spec/blob/master/SPECIFICATION.md
Let me know how it goes,
Brian