"I would like that cake."
Translation:Querría ese pastel.
Quisiera, is what you would use in Spain, if you were being very polite. Querría, translates as I would want... I think it's wrong to use this form, because it's conditional. Maybe it's antiquated form used wherever the Duo developer comes from...
In that case, how would YOU express the idea presented here; i.e., 'I would like (to have) that cake'?
She already suggested Quisiera instead of Querría. The rest of the sentence could stay the same.