Hope to understand your question, because you talk about HTML files, which means HTML output but they did still have SWF components? When publishing to HTML you should have gotten a warning about those components.

It if is confusing terminology, but you want to publish legacy projects which had SWF output, now to HTML output it may be not so simple as just publish them to HTML. Use the HTML tracker under the Project menu to check for incompatible items and replace or delete those. Beware: each rollover will be indicated as non-compatible which is no completely true. Rollover captions and images will work fine on devices which have hover events: desktop/laptops using a trackpad or mouse. Rollover slidelets will not be supported.

More information in:

http://blog.lilybiri.com/using-cpquizinfoanswerchoice-for-survey-conversion-from-swf-to-html

If you have published courses set up for SWF output, you will need to republish the courses in a strictly HTML5 format. Any Adobe Captivate projects that were published with SWF output will not work in today’s environment. Additionally, the player required has been disabled by Adobe as Adobe no longer supports the SWF format.