The breadcrumb is actually a client side widget while the microflow is server side logic so i don't think you want to to mix these two up.
The problem here is, that the home button on the navbar clears the content pane, resulting in a clean breadcrumb path. But when you use a button to open a form it just stacks your form on top of the other form. The good thing is that if you use the close form button your older folder will automatically return, as you just removed 1 form from your stack. The bad thing (for you) is that this means that the breadcrumb will show forms double as it is just a representation of the form stack.
I think that the best sollution for now would be to create a custom button widget that cleans this stack and performs a microflow afterwards. Kinda like the home button does now.