"He showed me something very important."
Translation:On pokazał mi coś bardzo ważnego.
Why is "On pokazał mnie coś bardzo ważnego" marked as wrong? https://context.reverso.net/t%C5%82umaczenie/polski-angielski/pokaza%C5%82+mnie
"Mi" is an unaccented (non-emphatic) object pronoun, so it doesn't belong at the beginning of the sentence.
More and more natives start sentences with "mi", as its emphatic counterpart "mnie" is falling out of use. But we're not ready to accept this (yet), as it's not generally regarded as correct usage.