It is so strange to me when people get downvoted for suggesting a possible solution is to volunteer some effort. HN is all about open source until someone mentions creating a PR or even just a simple issue. Is this forum the definitive spot for complaining about software?

Filing an issue on GitHub is the correct thing to do. It has higher visibility for a longer period of time than a hacker news comment and is more likely to resolve the issue while wasting less time of the maintainer's and anyone else using the software.

edit: It seems you've been upvoted back to normal. Ignore me.

isn't "show hn" also meant to get some feedback? responding to feedback with a counterrequest seems off

If it were a product or merely a project, you would be correct. But, open source software has too many users who think they are owed free features as it is. What's more, there's a high possibility that people on this particular forum actually have the skills to implement a proper PR. Finally, their comment clearly wasn't meant as a dismissive counter request but rather as an invitation for mutual excitement, and even an admission that the criticism was correct, but would be better served on the Github repository.