Unfortunately we're not in a position to create 'categories' for threads... we change the colour if the thread is sticky, or not, but we can't have different colours for different threads otherwise.
You could always do something like:
[Official] Beta mission 1
[UnOfficial] Beta mission 2
in the thread titles if you'd like. Of course, this would be completely voluntary by all posters on that forum.
Otherwise you'll still have to click on the thread and scroll down until you see the required addons listed