"She was a wonderful friend."
Translation:Ba chara iontach í.
go is only used with those adjectives when they're used with a form of bí. If they're used with is, you won't need the go. Also, a note: if this sentence was said out of the blue, native speakers would parse it as "She would be a wonderful friend". The past tense interpretation of the copula is the marked form, where as the conditional is the unmarked.
I’m not following what you mean by “marked form” and “unmarked form” of the copula — would you explain it further?
The "unmarked form" is basically the general interpretation - the one that is normally used, and would be assumed out of the blue. The "marked" form is the one used in special cases.
Thanks — as far as I could tell, there was no difference in the written forms of conditional ba vs. past ba, so I was wondering if marked/unmarked had to do with a written difference that I’d missed.
Nope. Though a note from An Teanga Bheo: Ghaeilge Chonnamara: Is minic nach mbíonn séimhiú ar lorg ba (foirm stairiúil na copaile): ba fear maith é... Ach, bíonn séimhiú de ghnáth ar aidiachtaí áirithe: ba bhreá... There's also some interesting stuff to note on GnaG, though it doesn't refer to the plain form of the preterite/conditional, but to conjunctions, questions, etc.
Also, as to markedness, it's just a linguistics term I've found useful. Here's the Wikipedia entry
So how do I get around the interpretation as conditional? Could I say something like "bhí sí ina cara iontach", or would that refer to one specific point in the past rather than to a general attribute of her?
So I could use this sentence, say, at a funeral to say that she was a wonderful friend to pay for piano lesson for my kid when I couldn't afford them? (I'm not trying to be funny, just to come up with a sentence that is both clearly past and clearly not past habitual.)
BTW, I'm kind of a grammar nerd and love this kind of discussion--it's probably why I'm tongue-tied when trying to speak Irish.