Swapping hero powers, like through playing a hero card, removes the hero power cost reduction awarded from Hunter’s questline, and that’s fine and working as intended per the text of the questline reward “Take the High Ground”.
When the hero power reduction part of the questline is achieved AFTER Reno, Lone Ranger is played, however, it reduces the cost of the current bullet equipped, but then the reduction is removed as soon as you end your turn. Video of it taking place :
Reno’s hero power reads that it “Swaps each turn”; is the intended interaction to remove the cost reduction in this case when the swap happens on end turn as each bullet is meant to be its own hero power or is the intended interaction to maintain the cost reduction since the hero power hasn’t changed since it’s still Reno’s hero power “Reno’s
Personally, I’d prefer that it’d work in the latter aforementioned way for the sake of fun. It’s an interesting question, nonetheless, and there’s not a precedent for it unless you stole the Dr. Boom hero from Warrior, played it, then completed the questline reward.