Not noticing any visible changes makes sense, especially when considering the scale of the project. As far as I'm aware, the dev is solo in everything besides Voices. Meaning that all coding, scripting, dialog, translations, gameplay, and overall scale is up to him. This includes the fact that when talking about updates in the past, the Dev had 3 planned total(i think, its been almost a year since ive seen the dev talk about the overall plan). These updates would be astronomically sized compared to other creators, and thus would take more time to complete.
Talking about the update sizes, coming from the dev, each update promised huge amounts of content. The next update has been described as doubling the current content available, and any other updates would have similar effect where they add so much.
Here is what I can tell you. I've been monitoring the Trello site for the better half of the last year, and it does move, but only ever so slightly. From the thousands of messages wondering if the dev is alive, if HHG is ever gonna get updated, and others asking if they can help, the dev has been exhausted by everyone, and can but won't just answer every message about the game. Now I have typed your eyes off if you even bother to read this, I hope it helps in any way possible. Sadly to say, patience will be our best friend and only comfort in waiting for HHG to update