Guaranteed or faster way to find Torkild in filial bonds quest
Solution 1:
There is no guaranteed way of finding him, he doesn't even have a refID to travel to since he only spawns during the random encounter.
Out of all the travel points, the glacial cave point seems to have the best chance to trigger him.
However, there's a chance you may have encountered him somewhere and he's dead dead already and you just didn't notice the corpse. Having the unofficial dragonborn patch will prevent this.
Finally, you can always use the console command to advance the quest:
setstage DLC2WB01 20
You may need to add the letter to your inventory first:
player.additem xx026562
where XX is the mod load # for your dragonborn DLC