"I think that he will be fine."
Translation:Mi pensas, ke li fartos bone.
No, it's not. Bonega means "very (or bigly) good" and we are not being asked for degrees of fineness, so bonege would also be in error. What we are supposed to be modifying here is farti not esti (even though esti is apparently now accepted) and farti is all about how one is feeling.
Mi esperas, ke tiu helpas.