Can't say i've experienced the archers shooting while running, but given that they can't get stunlocked anymore, it means after every time they get hit, their AI runs away immediately, and you have a chance of making them flee to their spawn. If they flee back to their spawn instead of running to the sides, they won't have a free pathing anymore to run from you, meaning they will keep looping the shooting command if they're cornered, spamming arrows at you which in turn can stunlock you.
Regarding the general difficulty, i never got the feeling that archers are ever difficult or more sporadic during different time periods of the day. They always seemed the same for me, with random accuracy where sometimes they miss, sometimes they hit. I'm still not sure if the double hit thing is a bug or not, it seems to happen randomly for me, even at close or longer range when i attack. Initially i thought the double hit mostly works only if you attack them while they have the yellow outline visual cue that tells you they're going to shoot, but it can happen outside of it.
I managed to barely get it at 44 seconds yesterday, so it still seems doable at that time, albeit the last one has to spawn in the same place you kill the previous one, giving you a 1/3 chance compared to the 2/3 chance in the past. Even then i still don't always get the last
archer after trying again today. If you attack an archer too early after they spawn, they seem to flee back to their spawn instead of running to the sides, prompting the looping attack that can stunlock you. This happens more often to the bottom archer spawn, since they're the ones we can reach them earlier compared to the sides.