Yes - the point being that this and any good digital dictionary will cross-refer you to the base word, and show you the options if there are any. For example, if you look up fach it will immediately give you options of
Before digital dictionaries you had to be aware of what the possibilities were and then look them all up.
I felt the pain particularly as I came from a background of Gaelic and Irish where they use special spelling conventions so that as soon as you see a word you know what the base form and the mutation are.
I have listened to the speech several times and I am certain it is saying fach (although actually it sounds more like fâ) on the fast speech, but bach on the slow speech. The fast speech on the question is the same as what you get if you click the speaker top left of this page. What does anyone else think? If you heard it with the first word removed (so you could not tell from context) would you be able to tell?