"After she went."
Translation:Ar ôl iddi hi fynd.
Nope. The pattern with a subject is always:
ar ôl + i + subject + verbnoun (with soft mutation)
ar ôl iddi hi fynd
This is also tenseless, so it means "after she goes/went/had gone etc." You could almost translate it as "After her going".
"Went" is the past tense of "go" but "fynd" is the present tense.. Is the present tense always used after "ar ol"?
mynd is the verbal noun, which is similar to the infinitive in some ways - so it's neither present nor past nor future, necessarily.
In dw i'n mynd, for example, it's "I am going" (present continuous); in dw i wedi mynd, it's "I have gone" (present perfect). The mynd itself does not show the tense. (And fynd is just a mutated form of mynd.)
Also correct, yes, although it's more formal to drop the person. It's also common to say it like this in some dialects too, but that's a bit beyond the scope of Duolingo.
Which lesson covers i becoming iddi in this circumstance? Imma have to look it up in the notes.