Even just the English names for the letters helps “thorn” and “eth” IIRC welsh uses a doubled d for the eth sound, hence I once had a coworker whose name was D

Even just the English names for the letters helps “thorn” and “eth” IIRC welsh uses a doubled d for the eth sound, hence I once had a coworker whose name was Dydd (pronounced deathe to rhyme with breathe) shortened from Meredydd (usually rendered as Meredith in English)