Is your forum working in a genuine RTL environment (i.e. as shown for Hebrew or Arabic) or in an LTR environment with a few RTL writings?
My forum is working in LTR environment. I've only added a 'Category' for Hebrew readers, and for this specific category I really need the RTL BBcode feature; as well as for adding some Hebrew text inside English posts.
There is no need for "perfect" support for RTL languages, as far as I concerned.
There is no need for it for your personal case. But we develop the forum not only for your case and if the feature exists, it has to work everywhere in every scenario.
As addition because of my suggestion to set the writing direction for the wohle page in
<html>. This is not necessary because the forum script does it by itself with the value of
dir from the language file (linked example from the tamil language file and the line of the main template to place the value in).
Trenne niemals Müll, denn er hat nur eine Silbe!