"After she went, I went home."
Translation:Ar ôl iddi hi fynd, es i adre.
I'm not entirely sure why (from a grammatical point of view), but it's just not the case in Cymraeg; the "es i" would give "flavour" to the translation in Saesneg being "past" and therefore the "ar ôl iddi hi fynd" would also need to be in the past tense. I was once taught that "i fi, i ti, i chi, iddo fe, iddi hi, iddyn ni, iddyn nhw" are "timeless", just like "cyn"...
Aeth e i'r tŷ bach cyn iddo fe adael - He went to the toilet before he LEFT (not LEAVES).