"She does not like him at all."
Translation:Dydy hi ddim yn hoffi e o gwbl.
Nope. Personal pronouns have a number of forms but most are determined by what they follow e.g. a consonant or vowel, a simple or compound preposition etc.
"Dyw hi ddim yn hoffi e o gwbl" is also expected as a correct answer (in the check-all-correct-answers exercise). Where is this form mentioned or explained in the grammar notes? I can't find it anywhere.
The first word "Dyw". It's different from the answer given above ("Dydy . . "). And both versions were required for the answer to be correct.
"Dydy" is north waliau'n whereas "Dyw" is more typical of the south. They come from the more traditional form "Nad yw" and "Nad ydy". EDIT: Shwmae is correct. Bad habit of mine using "Nad" instead of "Nid".