If you want to draw attention to a question you should just reply in that topic to bump it up the topic list (within reason).
If you don’t get any answers to your question (which is really rare on here) you might want to think about improving your question. In case of the linked question it might be helpful to make it a little bit more focused and maybe show a small example of your problem (but I have no idea about policy learning so maybe the question is clearer than I think!)