"It is bizarre that you not be aware of her wedding."
Translation:C'est bizarre que vous ne soyez pas au courant pour son mariage.
There is a nuance here that Duo has not taken into account:
1- you are right "au courant DE son mariage" means "aware of her wedding": you were not aware that she was getting married.
2- "au courant POUR son mariage" means "aware ABOUT her wedding": depending on context, that could mean that the wedding was cancelled at the last minute or that the celebration was eventful, etc. but in any case that something happened or did not happen.