The answer is silly and wrong. 汤圆 = rice balls, not dumplings and the name definitely does not say sweet. Answer should be "These rice balls are too sweet!"
I agree with you Wilson wholeheartedly. I also learned rice balls as the translation in our Chinese class.
我记得在其他课程里，汤圆可以翻译成stricky rice dumplings, 或者stricky rice balls
太甜了是英文的really sweet.不一定是too sweet。而且我们英语母语的人把汤圆直接翻译成tang yuan不说dumpling。