BUT in the show's continuity (unarguably different from the books given Sharpe's Yorkshire backstory in Justice) this still means that Hakeswill doesn't actually kill Harry Price because he survives and returns to fight in Waterloo. (After all, you can't argue that Ducos is killed in Honour!)
As for the original question... Hakeswill returns in Enemy, where he kills a British captain and Teresa. It's also implied that he killed a British colonel at some point prior to the episode and stole his uniform. I understand his appearances in the books were far more carnage-inducing, however..
I suspect the problem is that you have too many paperclips up your nose
Hakeswill didn't kill the officer in the trench for no reason, he did it because he was trying to get him up to go through the castle wall breech and as Hakeswill was a coward he killed him and then hid under the dead corpses.