Programmers maintain and evolve their software in a variety of programming languages to take advantage of various control/data abstractions and legacy libraries. The programming language ecosystem has diversified over the last few decades, and non-trivial programs are likely to be written in more than a single language. Unfortunately, language interfaces such as Java Native Interface and Python/C are difficult to use correctly and the scope of fault localization goes beyond language boundaries, which makes debugging multilingual bugs challenging. To overcome the aforementioned limitations, we propose a mutation-based fault localization technique for real-world multilingual programs. To improve the accuracy of locating multilingual bugs, we have developed and applied new mutation operators as well as conventional mutation operators. The results of the empirical evaluation for six non-trivial real-world multilingual bugs are promising in that the proposed technique identifies the buggy statements as the most suspicious statements for all six bugs.