You can just submit the topic one more time, typically moderator will do a macroexpand if the topic is appearing more than once. But the problem is that the sub

You can just submit the topic one more time, typically moderator will do a macroexpand if the topic is appearing more than once. But the problem is that the substack link stopped working, so at least you need to find the content somewhere else. Another option is just to use your own blog for writing your meaningful bits of information and then submit a new link. I have never noticed that an old topics are not available for answering, but I appreciate it because if they would be available, the macroexpand can not work as intended. Also I never read more than 1 page of "threads", so what you want to do is writing to a void.