In the lesson AKO098 Caro-Kann Defence 4....Nd7 there is an error in the text for one of the move tries. In the position below I tried 6.Qf3, the text states that this move loses time after 6....Nxe4 7.Qxe4 Nf6, but this overlooks that after 6....Nxe4 white has 7.Qxf7#.

Yes, you are very correct. That response is totally wrong. I have edited the response to something more correct. It seems 6. Qf3 is not the best move still as it occupies the f3 square which is the best place for your Knight on g1 and black is not forced at all to move the Knight from f6 so the threats on f7 are really phantom threats. So there should be a more reasonable response in the lesson now after trying this move.

I think that some of the reponses are a bit lazy e.g. You have missed the  point.Try again. Or -Your move does not achieve anything.Try again.