As we all know, RHP is a very international lot.
For those who speak other languages, it seems to me that the forums are very english-centric. Perhaps if those who spoke other languages had an easier time identifying which threads they could understand and respond to, they would be more inclined to become active posters.
So down to the random idea.
Rather than the present small dot at the start of the thread title, consider a flag indicating the thread language (perhaps keep the dot for english, as do we mean US or UK?, and a lot of flags would hide the likely small number of non-english flags/threads. We could revise that if the number of non-english threads took off).
Then when the thread is created, add a field hread language, default english, so that the thread creator can specify what language they are going to use.