Understanding Why My Answer Was Scored Incorrect

Hola Rich

"tener paladar dulce" is not something we'd say in Spain or Latin America to express "to have a sweet tooth" - it's grammatically correct but it'd be a sort of literal translation that you wouldn't probably hear there. For this, the most common expressions to use would be "ser goloso/-a" or "tener debilidad por los dulces" or even "me encantan los dulces". 

I hope it clarified it.

Saludos cordiales

Inma