I tried to add Japanese text into ships.tbl and encountered encoding error.
I'm using fs2_open_3_8_1_20171206_8168099_x64_SSE2-FASTDBG.exe and fs2_open_3_8_1_unicodeSupport_x64_SSE2-FASTDBG.exe.
Actually most characters are fine. Only some of them cause problem.
At first it seems completely random. However, I found a pattern when I made this list:
Every 6-letter UTF-8 character code which contains "80" gives encoding error.
I picked up some arbitrary characters for testing. Seemingly my hypothesis holds true.
I guess other languages (such as Chinese and Korean) will have the same problem.
I hope this information helps. Keep up the good work.