At least I assume they are bugs, but be happy to be told otherwise…
Mostly minor things, but very repeatable. The forum code does not seem to keep track of posts that you have not seen very well. For example, when looking at the General Fruit Growing category I might see 4 or five unread/new threads. If then go and select all categories, I would expect to see those general fruit growing thread just up as well as possibly others. Nope, often the original threads up in a more selective category disappear in “all categories”. Along this same line, often just hitting the Latest button will have a similar effect, those unread thread go away (and no they haven’t just moved down in the list due to more recent ones).
Perhaps related, New will often show some number of threads in ()'s after it, however if I select the New button there are no threads there???
Not awful and I have largely learned to work around these “features”. But if @scottfsmith was doing a rebuild anytime soon, might be interesting to see of there are any fixes for these.