I regret implementing user-defined leader titles is not as easy as it seems...
Even if you assign the new names as described in the rules.txt, Civ2 will ignore this in most cases.
I had my problems with that matter, too - until Gothmog helped me out (Thank you!!!):
You have to switch the "adjective" and "plural" entry of the nation you want to give personal names.
For a detailled instruction refer to the "Getting Leader Titles Right" tip available on his website:
http://members.xoom.com/fambans/index.html