If you want subtitles that use non ASCII characters in a DVD, you need a VobSub file (.sub + .idx) of the foreign subtitles as well as a .srt file of the subtitles, which can be in any language.

You make a folder for your subtitles, you can call it Subtitles, and go into SubResync, which is a VobSub program. Open the VobSub file, and don't edit it. Just save it as a .son file in the Subtitles folder. This will create a bunch of images of the subtitles and a .son file that DVDMaestro can use that contains the timings and junk.

Next, since you are making a DVD, the framerate of the .m2v file would be different from the framerate of the .son file. Open Subtitle Workshop and open the .srt file of the subtitles. The only reason you need that file is because it contains the timings for the subtitles. Change the FPS of the subtitles to 24, and the Input FPS to 23,976 or 23,981. Then, save the subtitles as a .son file. Then, replace the original .son file made from the VobSub program to the newly made .son file, which contains the new timings. Then, go into DVDMaestro and import those subtitles, and it will work if you did everything correctly.