When you read the translation of a text and the content is not really clear, then there is most likely to be a mistranslation there.
ご質問ありがとうございます。
"When you read the translation of a text"=「あるテキストの翻訳を読み」
"and the content is not really clear,"=「そして内容があまりはっきりしないとき」
"then there is most likely to be a mistranslation there."=「そこには誤訳があるだろう。」
ご参考までに。