Welcome to the forum!
Your prompt is indeed somewhat complex, the Gemini models respond well if you give them a few examples to start them out.
You could be running into a peculiar problem with Korean reported here: Gemini Stop responding when certain Korean word(normally used or a typical person name) is included in the system instruction or user prompt
One way to check is to look for instances of the pattern that the post describes as problematic. Another quick way to check is to remove Korean from the target languages and see if that makes the OTHER problem go away.
The finishReason OTHER has issues, in my opinion.