In terms of writing fiction, Irish has been the bane of my life. It's my own fault; I'm lazy--or perhaps impatient is a better word--when in the grip of the work.
Twenty years ago, when I was writing Ammonite, I created an isolated tribe based on the Mongols. I was hot on the trail of the story, and used placeholder proper nouns based on Gaelic vocabulary. I meant to do the necessary research later and swap out the placeholders for the real words.
But here's the thing about fiction. It doesn't always work according to plan. The characters took on the attributes of their names. I couldn't change the Echraidhe to, say, the Buriyads, or Uaithne for, oh I don't know, Miroslava. It was too late.
Reading through Hild again, I've discovered I'm about to commit the same mistake. Early on in the book, when Hild is about ten, she encounters an old and damaged Irishman who speaks very little Anglisc (Old English). In a cursory online search I couldn't find the Old Irish I needed so I scooped up a hodge-podge of Irish words of dubious provenance, plunked them down, and surged on.
Here's how that passage reads:
The water slapped, the canes rattled, and man, girl, and dog all looked at the sky--clouds piling together, no longer tin but lead--then each other. Hild, encouraged, stood, came closer--oh, her shoes were more mudcake than leather now--and pointed at the willow man, at his white crinkly hair, and said one of the Irish words she knew, "Bán."
And he laughed toothlessly, then loosed a torrent of Irish at her. His accent was strange. She understood three words of it, cailín, maid, Sasanach, Anglisc, and ocrach, hungry, and shook her head. "Go mall," she said, slowly, and "le do thoil," please, and he said it all again. "Go mall," she said again, "lo do thoil." And Madra tilted his head and whined, and then Bán spoke one more time in a jumbled Anglisc/British/Irish mix, and Hild listened with her whole skin, the way she listened to rooks in the field or wind in the trees. She understood, she thought. He was asking her if she was hungry.
She sat in the mud--Onnen would scold her raw--offered a fist to Madra, the first dog she had allowed near her since she watched Od eat the guts of Osric's man, and repeated back to Bán as well as she could, with the words he had used, that she, the Anglisc maid, whose name was Hild, was hungry, a little, but that when she returned she would be very well provided for. And he nodded, but shook his fingers dismissively in that Irish way, just like Fursey, and tutted, and unfastened the sack at his waist and offered her half his cheese and a bite of onion, and a dip in the coarse grey salt collected in the seam of his sack.