Well, hello there...
Man is that deeply engrained. You may notice some things don't quite look or work right. I'm real sorry about that. For the most part, not much is going on in this version of the code. Instead, things were moving forward (before this whole pandemic got started) over at the tsn9 demo site: https://the-spot.net/phorums/tsn.
I actually had gotten started on the new design, new concept thing from the previous thread, but given the mockup I did in 2015 and the way the internet moved on around 2020, things went to a lighter place. I did manage to start delivering on the concepts I showed in the mockup (go check it out), but I found myself actually rewriting the entirety of phpBB to deliver it. To make matters worse, they dropped a huge update to the software, and it isn't compatible with the version we're running. So I just set it all aside until I care to spend my free time doing what I am already doing all day at work.
I'm pretty proud of what I was able to do, as it were, but the further I got into it, the more it felt like a very elaborate wireframe/proof-of-concept. I didn't have a proper design in mind beyond the Material Design guidelines, and feature implementations. I need to sit down and put together a specific visual before I go much further, and also probably start over using the new platform if there is a migration path available.
For now, the posting and reading still works on this version of the template, there are just some decorations that aren't quite all there, and apparently some BBCode functions (like URL)