I am using Filemaker Pro 12 and having the same problem with Korean characters.
They appear as squares when converted to PDF. Not sure if you had any luck with your problem.
Can't seem to find the solution to this problem. I am sure Filemaker is aware of the problem but so far there seems to be no solutions yet.
I will be grad if there is a solution.
I reported a similar issue few months ago to FMI (France) phone support. I created a little database that demonstrate the limits of Save as PDF command compared with FMP preview mode for instance.
It is also interesting to compare different fonts and plateforms.
I know well it cannot help you very much but maybe could help FMI to figuring this issue.
Note : this was programmed in French langage and now quickly traduced in english. Excuse me for approximations.