A typo is an error that could be made during the process of translation, but it's not a translation error, it's not something that's lost in translation or mistranslated.
I think the question whether a typo occuring during translation is a translation error is mostly a matter of perspective. If you ordered the translation and it contains a typo not present in the original article, that's an error in the translation so it's fair to consider it a translation error.