"Ges i frecwast ar ôl iddi hi fynd."
Translation:I had breakfast after she went.
Why does 'iddi hi fynd' form the past tense?? These weren't in the past tense lessons from earlier....
Here, too, "ar ôl i" (after) doesn't indicate tense at all -- just the context determines whether it's "after she went" (past) or "after she goes" (present or future).
You know that it should be "after she went" here because the first verb "Ces" is in the past tense and therefore you must be speaking about the past.