It’s possible, though I don’t have a tool to recommend.
That won’t be added to the Workflow because it’s really niche and would essentially be a whole new Workflow. In almost a decade since the Workflow has existed, it’s the first time that has come up. Its purpose is to convert Markdown to BBCode for use in this forum; everything else (HTML and RTF) is icing on the cake.
Even if you only wanted to keep those tags, you’d still have to purposefully ignore all others so they don’t remain in the final result and you’d have to make deliberate decisions on formatting.
