As you know, you can create a URL that will open a new topic composer. You could make that be the link added by the theme component.
I don’t think that it’s possible to do that without adding code to the theme component (but maybe it is?). Maybe someone has an idea about that and will offer that solution here (or on the other topic). If not, you can contact me or post in Marketplace with the description of what you need and a budget.