The project is indeed closed-source. Personally I've had experiences where I found the project moved forward towards the roadmap much faster - specifically when considering smaller-scale projects that are UI heavy and therefore take in many UI changes in parallel - when I instead implemented feature requests and focused most of my energy on listening to user feedback rather than reviewing code. UI polish can be quite tricky when it comes from many sources :)
That said, nothing is set in stone! If at some point there are enough feature requests to where I am the bottleneck, this is something I would revisit.
I'd be happy to hop on the Discord as well!
This is how SQLite is developed, for example.
As for information about me, you can search the internet for my username. Let me know if you don't find anything and I can try to help. I'm not going to share information about others on the Discord server.
"I didn't ask for their name" is a ridiculous reply. You asked for some unspecified degree of personal information. Luckily the author didn't bow to your pressure but just said "I'm a software developer", which we already knew because of the developed software.
Why don't I have standing to demand people's dox as some random idiot Internet commenter? Answer this question and then turn your answer around on yourself. Then, maybe, apologize? Or don't, if you have some other way to psychologically ensure you won't go around demanding people's information in the future.
If one wants to be extra "there's nothing up my sleeve" they could also publish instructions for how to do reproducible builds for the compiled artifacts (which does require publishing the source code however).
It was mentioned on the JJ Discord server that there doesn't seem to be any information available about who you are. Especially since the project seems to be closed-source, perhaps you could share some information about who you are in order to build trust.
I hope you understand. I think users may hesitate to download and install the application without knowing anything about its publisher.