Let me introduce the Japanese "S's for seasoning". Five condiments are widely used in Japanese food (和食・わしょく), and they are all starting with S in Japanese:
せ：醤油・せうゆ (soy sauce)
Notice that the pronunciation せうゆ is said to be the archaic pronunciation, but some people think that this is just used to put all s- syllables together. Anyway you should use しょうゆ as a correct pronunciation in modern Japanese.
I have called it shouyu since I could talk! My problem is getting used to answering "soy sauce". We never use that phrase in my house! But everyone looks at us weird when we ask for shouyu, but I can never remember the English word for it. ("You know... The black liquid you put on rice? Shouyu!")
Sushi, teriyaki and bento are the standard English terms. Shoyu seems to be a regional thing. In standard American English, which Duolingo uses, it's soy sauce. Duo's only going to accept the words it knows about. If you know words Duo doesn't, make sure to flag it and let the developers know.