According to Wikipedia, "the name of the dish is a homophone for union ... ... 团圆; pinyin: tuányuán)"
Whoever wrote that drivel clearly doesn't know what a homophone is because that ain't one! Also, 团圆 doesn't mean 'union'. It means 'family reunion'. And today, there are precious few reunions on the Lantern Festival. Quite the opposite. Most people will have returned to work by then.
It then goes on to say "The round shape of the balls and the bowls in which they are served symbolize family cohesion." Maybe once; not now.
The Lantern Festival is held on the first full moon of the lunisolar calendar. The balls resemble the moon.