NodeBB address in use, exiting... Error: listen EADDRINUSE 0.0.0.0:4567
This usually means that NodeBB is already running. Use ./nodebb stop and if you still have the issue look up "kill process on port" with a search engine.
A couple of years ago, Google contacted me by phone (Google News) and instructed us that we should not have more than one H1 tag on the same page. H1 tags are clearly used by Google to discover the major headline of a page.
I'm not sure how useful this information is, but I noticed that every page has multiple H1 tags.
A couple of years ago there was also a lower adoption of html5 elements. Having one h1 tag per page is still a good Idea in general, but it is allowable to have one h1 tag per containing article tag as well. Since this theme does not seem to use tags like article and aside (that I've seen in my quick check) I agree that there should only be one h1 tag per page which contains the page title or headline. The theme structure is otherwise good, but could definitely use with some contextual revamping of quite a few divs.