"Θυμάμαι τους εαυτούς μας."
Translation:I remember us.
Yes, it would need paraphrasing which would have nothing to do with the grammar being taught. Something on the line of: "I remember when we were young..." Or perhaps substitute something better. Thanks for bringing it to our attention. It's one of those "lost in translation" moments.
As others have mentioned, I can confirm as a native English-speaker that the translation of this phrase sounds decidedly ungrammatical. I cannot think of any situation in which I would say "I remember ourselves." I can indeed say "I remember US" (with the object pronoun rather than the reflexive) but even that is a bit of a stretch (e.g. Me: "I remember (us) when we were young and played in the park. Do you?" You: "Yes, I remember (us).") Linguistically, this phrase violates anaphoric binding- the usage of "ourselves" necessitates the explicit presence of a matching antecedent- in this case it would have to be "we" (i.e. "we remember ourselves").