This is volume X of the transactions of the Gaelic Society of Inverness, Scotland. The lyrics are on page 265, dated 25 April 1883, giving some idea of how far back the song goes.
I haven't found a translation but wrestled with my tiny store of Gaelic and a lot of help from An Faclair Beag, the online dictionary. So this is a very free translation but I think it captures the spirit.
There's a version on YouTube, dated 2013: https://www.youtube.com/watch?v=JOXIhGk6Gko, which looks like an LP featuring Donald Ross, William Burnett, Simon Thoumire. The YouTube version don't match the verses I've put here.
I hiù ro hò, i ho ro hò Nis cuiridh mi luinneag an òrdugh dhuibh. I hiù ro hò, i ho ro hò Air pòsadh piuthar Iain Bhàin.
** (First and third lines of the sèist [chorus] are vocables, like Gaelic tra la la) ** Now I'll make a proper song for you ** About the wedding of Iain Bhàin's sister.
Nuair chaidh sinn a-mach ris na h-aonaichean, Bha ceò, bha sneachda, bha gaoth againn, 'S bha sinne cho geal ris na faoileagan Air pòsadh piuthar Iain Bhàin.
** When we headed out to the steep places ** There was fog, there was snow, there was wind (we had) * ** And we were as white as seagulls ** At the wedding of Iain Bhàin's sister.
* "Againn," literally at-us, is used for possession, but I feel that the meaning is "what there was [what we had was] fog, and snow, and rain."
Nuair ràinig sinn urad bha an oidhche againn, Taigh fada gun solas gun soills' againn, Chan fhaigheamaid fiù na coinnlearan, Bh' aig pòsadh piuthar Iain Bhàin.
** When we first (finally) got there, it was night we had ** A long house without light, without brightness we had ** We couldn't even get candlesticks (candles?) ** At the wedding of Iain Bhàin's sister.
Ach marbhphaisg air an fhear-chiùil a bh' ann, 'S cha b' fheàrr dad idir an t-ùrlar a bh' ann, Dol fodha gu ruige nan glùinean ann, Aig pòsadh piuthar Iain Bhàin.
** A curse on the musician there ** And the floor was no good at all ** Sinking to your knees ** At the wedding of Iain Bhàin's sister.
( "an t-ùrlar, of (the) floor" is almost certainly a pun. It means flooring, like a dance floor; but it can also mean the theme of a piece of music -- in a sense, "the beat of the music was bad, and the floor was pretty beat up, too")
Am beagan a bha de na h-uaislean ann, Chan itheadh iad nì le uaibhreachas, 'S mun tàinig a' mhadainn bu truagh leibh iad, Aig pòsadh piuthar Iain Bhàin.
** Some of the gentry were there ** Not eating a thing, out of pride ** In case by morning they'd be miserable ** At the wedding of Iain Bhàin's sister.
(They weren't eating because they didn't want to get sick, that was the kind of food we had)
Ach chuireadh gu grad ann an ordugh sinn, ‘Us shuidh sinn ‘n ar prasgan mu’n bhord a bh’ann ‘S bha droch mhac-na-bracha ga ol again, Aig posadh piuthar Iain Bhain.
** Oh, as soon as we got settled ** And were sitting in a gang around a table ** Then, bad single-malt drink appeared on it ** At the wedding of Iain Bhàin's sister.