"She ate chips today."
Translation:Mi wnaeth hi fwyta sglodion heddiw.
in conversational welsh is the form of 'bwysais i' / 'bwytodd hi' any more or less likely to be heard than 'ges i bwyta' / 'gaeth hi bwyta'? i was speaking to one of my friends from gwynedd and she chastised me for trying to conjugate a certain verb the first way (bwytais i / edrychais i / &c), and told me instead to just use the 'ges i bwyta' &c form.
(edited) The forms using gwneud are very common in informal Welsh, especially in conversation. The short forms of mynd, dod, cael and a few other common verbs are often used in conversation, though - ask your friend which forms she uses in which situations.
Actual usage in the wild varies quite a lot with dialect and with level of formality. Once you understand the basic patterns you can just vary which ones you use in particular situations.
Then tell your friend she's wrong; "ges i fwyta" literally means "I had (my) eating" which doesn't mean anything in either languages. Depending on where you live or learn, you'll hear "Nes i fwya/Gwnes i fwyta/Bwytais i/Bwyteais i" etc for "I ate".
She ate chips today:
"Naeth hi fwyta sglodion heddiw/Gwnaeth hi fwyta sglodion heddiw/Bwytaodd hi sglodion heddiw/Bwytodd hi sglodion heddiw"