Often if you type the meaning instead of the reading, you won’t be able to enter it, because many English words don’t convert to acceptable kana.
Presumably you’re experiencing this mostly with typing the reading in place of the meaning.
You’re right that the obvious solution is to just slow down!
But if you can’t control yourself, there’s the override script, that will let you ignore any incorrect input for any reason. Obviously you should use it with a modicum of self-control.