"An old cat."
Did you write seann chat (correct) or chat seann which it would have corrected to cat sean? Since that is only a one-letter error in each word it would have considered it two typos not an error. These questions are quite a Sudoku puzzle as it is often possible to use the tiles to get a sentence which is very close to another valid answer, even though that second valid answer cannot be made exactly with the tiles given. In that situation it will suggest that answer even though you did not have the tiles for it. I do not think these Sudoku puzzles help us learn Gaelic but there is nothing the mods can do about it because it is to do with the way Duolingo works.