Translation:We will eat glutinous rice balls during Spring Festival.
According to Wikipedia, 汤圆 seems to have two branches; 甜汤圆 and 咸汤圆. The former is sweet, while the latter salty. Baidu appears to insist that it is sweet. https://zh.wikipedia.org/wiki/%E6%B9%AF%E5%9C%93 https://baike.baidu.com/item/%E6%B1%A4%E5%9C%86/1333352
I am interested in a relation between 汤圆(or 元宵 in a strict sense) and 雑煮/zoni in Japan. The zoni is a soup with mochi, sticky rice cake, in it. This mochi is not sweet. The sweet one is called ぜんざい/zenzai or お汁粉/oshiruko. The former name is used in Kansai, the western part of Japan. The serving of this sweet one is not restricted in the new year period.
There is a similar relation between 红包 and お年玉/otoshidama in Japan. Both is an envelope with money in it and a traditional custom in the new year. The latter is not in a red color, though.
おにぎり/onigiri is totally different from 汤圆. It may be analog to sandwiches in the western world. I could not think of onigiri when I heard rice balls, but Google Translate seems to adopt this translation. Instead, I thought of 団子/dango, which might be translated as mochi balls. It is a sticky rice dessert.
"During the Spring Festival we eat tangyuan."
I'm not opposed to "sticky rice balls" or "sweet dumplings" or the like, but "glutinous rice balls", though technically okay, strikes me as really awkward.
As for "will", it's not necessary here, because "会" can denote a general predilection, which is sufficiently captured by the simple present in English.
No, there exists an enormous variety of foods that are all called "dumpling" in the English language. The ones I grew up eating in Australia were large, did not have a filling, and were cooked either in a vegetable soup as a main meal or in golden syrup as a dessert. I believe this kind comes from Scotland or northern England. Many other native English speakers would have no knowledge of that kind of dumpling. People with other backgrounds will know other kinds of dumplings that I've never see too. I never saw jiaozi/gyoza until I travelled to Japan and even then I hadn't yet seen them referred to as "dumplings". I learned that some years later.
To me, "rice balls" are a Japanese snack that's also available in Korea and Taiwan. They're more like zongzi but not sticky and are usually savoury rather than sweet. Often they have a seaweed wrapper. They don't always have a filling. Japanese name is onigiri, Korean is samgakgimbap. They're totally different to mochi. I never thought of them as dumplings either, but now that it's mentioned it does make sense.