Dev here. Thanks for being constructive in your comment/criticism. I fully understand where you're coming from with this, and said understanding is partly why I recently made a huge devlog over on our Patreon discussing the long wait for the chapter, steps we took to ensure that won't be the case for Radiant Ch5 and onward, etc.
Also... Chapter 4 is releasing this month (August).
There is something I wanted to address about what you said: Patreon is a subscription platform where many people pledge month to month, optionally paying far more than the average person and not getting that much in the way of "exclusive benefits" in return for doing so... which is why I am somewhat strict about sharing things there exclusively. It's not that I don't want others to have access to the things we share, so much as it is that I want to give back to our patrons.
With the above in mind, things like monthly wallpapers shouldn't be a surprise. As for long, detailed devlogs like the one I recently wrote, I do feel this is a big part of what makes it worth the average patron's while... but that doesn't mean I shouldn't do a better job communicating the fundamentals here on platforms like Itch, and I will try to be more mindful of that going forward.
P.S. There was a LOT of false statements and misinformation in the comments below. People suggesting we gave release dates that we did not, claiming we said things that we did not, etc. Try not to let said comments inform your views of us and the game: it will accomplish nothing but getting you riled up, which is good for no one. If you're ever curious about something, I can be reached on our official Discord and my DM's are always open/I reply to everyone.
P.S.S. While Ch4 has indeed taken a little over a year, the average chapter for this game will be approximately 4-5 months. This may still seem like a lot, but keep in mind that every game is different, and with Radiant being fairly complex in comparison to the average visual novel and having larger than normal updates, this is normal.