I think Tá/Níl were used (after some debate) as Yes/No on the Irish-language ballot papers in various recent constitutional referenda in Ireland.
(Gaelic in Scotland does not have the same official status as Irish in Ireland or Welsh in Wales, so the Scottish independence referendum ballots were only in English.)
Yes, they were. I can't remember the exact wording of the question, but I believe it was along the lines of "Are you in favour?" so the answer could be "I am/Tá", or "I am not/Níl". I could be wrong, so if somebody can remember the wording on the ballot paper, please don't hesitate to correct me.
(Gaelic in Scotland does not have the same official status as Irish in Ireland or Welsh in Wales, so the Scottish independence referendum ballots were only in English.)