Writing the dedication in language different than the language of a thesis or a book How is it received by the readers to see the dedication in, say, Chinese, while the entire other parts of the thesis or a book is in English?

Would that annoy the readers who do not know the language of the dedication?
Would that be considered as "putting private message in a publicly-designated document"?

Is there a reference that says whether this is a good/bad practice?
You're allowed to write a dedication in whatever language you'd like. Most readers skip the dedication page anyways, so it's not as if it's going to really influence their view. I'd find it interesting, myself, but others might be slightly confused to see a different language or alphabet. But I doubt many people would stop reading just because they saw something like that.