It has been two years since we last saw Stitcher Jim during the Heart of Fire tall tale, after opening a Chest of Rage and cursing his arm, we all know he will slowly become a skeleton and Flameheart saying he'll have "the strength of an Ashen Lord.", and we have no idea where Jim ran off to, nor do we know what he's doing. I might be guessing this, but I think he could either be somewhere in the Devil's Roar, or is hiding at Wanderer's Refuge at Wanda's secret cave where a Flameheart symbol is painted on a wall (which could be a sliding wall door lol) near the shrine where the dragon figurehead of the Burning Blade is.
Perhaps he is biding his time, growing stronger with the Ashen Curse, and could end up as a boss we have to fight.