The issue here is translating the saorbhriathar as the passive. It's really not a passive, but more equivalent to the English 'one'. '
But, you're also having the issue of equating English structure with Irish one. Just because something is the subject in English doesn't mean it has to be in Irish - as is this sentence, if you choose to interpret it as a passive. It's the same thing with Tá fíon agam - In Irish, fíon is the subject, but it's "I" in English.
Yes, but in Óladh fion sa Pholainn are you saying the subject is "one"? A lot more than one drank wine I would assume.
And even if so, how does that explain why the two sentences are structured differently? Was birthed, was drunk, sold, was eaten, was written. Do they function differently?
It's not 'one' as in 'one person only'. It's one' as in an agentless verb. Similar to the English passive, but not quite.
And the structure difference is because é is an object pronoun, which generally comes at the end of the clause (despite some of Duolingo's examples) when used by native speakers.