That's much too interesting a topic for drag to talk about here, and drag doesn't want to break the rules. If you use Lemmy's search system, drag is sure you can find the answer on your own.
Drag's partner hasn't tried drag's sushi yet, and is basing its opinion on store-bought sushi from America. Drag hates vinegar and would only put it in a recipe if absolutely necessary.
I think the store-made sushi usually has vinegar, which is sour, so if drag isn't using vinegar, then drag's partner might be OK with it.
If it's still too sour, then consider the following, which tend to be a lot sweeter:
Inari sushi - Inari's pretty easy, drag can just buy the tofu pockets and then drag can fill them with rice.
eel/unagi sushi with unagi sauce - Drag can buy unagi sauce in specialty stores.
tamago sushi, i.e. with a mini tamago egg omelette over the rice - Drag'd have to make tamago bc I don't think drag can just buy the omelette part, I only tried making it once but it wasn't that tough to do. Anyway if drag makes them, then drag can adjust the sugar levels as needed.