"I want to eat cake for dessert."
Translation:저는 후식으로 케이크를 먹고 싶어요.
You never require pronouns in Korean. They are often implied. You can't expect consistency between two languages that are fundamentally different.
Yet I agree there are still many alternative translations missing in this beta release, flag them whenever you encounter them. Thanks ;-)
As a side note, 나는 is also often used with this politeness level.