Translation:She will open the box and she will eat chocolate.
I translated this as "She will open the box and eat chocolate" ie dropping the repetitive "she will". This was rejected. To me this seems a perfectly natural us of ellipsis in English. I have reported that this alternative should be accepted as correct. I think it would be possible, also, to omit only the pronoun and leave in the second "will".
I think that it's probably best in this case to require the repetitive "she will", because that's the preferred structure in Irish, and while the course uses both backward and forward translations, the purpose of the course is for English speakers wishing to learn Irish, not for Irish speakers wishing to learn English.
It's a minor point, but I think that remaining focused on the preferred structure in Irish probably helps in the long run.