I am still not clear on that sorry for being so thick
in general switching languages should take care of that, however if you plan on doing that in a single post .. how about inserting an HTML for DIR in there? you could do that by adding a button in the editor or wherever call it LTR or RTL or both when clicked it inserts a the direction code
as for the letter cases you can add the char. code in that button too
.. the code for each language intended ... UTF8 or windows-1256 for arabic and so forth.
I do understand where the letter changes its shape wither that be start, middle, end of the word or alone
PS.. just make sure if you do that button idea to close each tag after the inteded effect, just like any bbcode buttons otherwise you will endup with a mess
I hope I got you right