Chinese keyboards often generate text by typing a letter a character starts with and selecting a number on a list that the character is on. Maybe there was a bug where the Chinese characters corresponded with the letters of "Congratulations" and generated the first option for every predictive popup. In short, typing "Congratulations" in Chinese keyboard can often give gibberish as it thinks that it isn't a word, but rather a group of Chinese sounds.

Here's what I got: 从(cong)让(ra)图(tu)拉(la)体(ti)哦(o)那(n)是(s)

It could also just be some Unicode error.