"ní mhaith liom" is incorrect. "Ní" is the copula, not the negative verbal particle (which does lenite).
I would have thought "ní mhaith liom" is "I wouldn't like" and "ní maith liom" is I don't like. As usual I have only baseless intuition to back it up. Can anyone disabuse me of my torrid notions?
It's a typo. You're correct Níor mhaith liom is conditional/past
An instructive error. If I understand it correctly : Ní as a particle lenites a verb: Ní bhuan an drochdhuine riamh; but ní as the negative of the copula does not lenite: Ní cuimhin liom cad a rinne mé aréir.
Ní bhíonn duolingo gan locht ná foghlaimeoirí gan tréith
Should "Taitníonn sé liom, ní thaitníonn a ghrúpa cairde liom." also be acceptable?
has the genitive always worked like this? X's Y vs X of Y is simply based on context?
You mean in English? Brandon's comment vs the comment of Brandon? The food of the dog versus the dog's food? A book cover versus a cover of a book?
Actually, that's backwards. X's Y would become Y of X and not X of Y.
Don's house == house of Don
The man's dog = dog of the man
The trouble is, it won't let you move on until you type in 'ni mhaith!'
So "cairde" is a plural genitive in this case?
For cara, the nominative plural and the genitive plural both take the same form - cairde. It is in the genitive in this sentence because of its position in the sentence, after another noun.