For error 68, check the error image in Summary tab by hovering over the word YES next it. Make sure those main accounts’ language settings are set to English, otherwise JV won’t be able to find the unfollow button and return an error.
For error 581, can you open EB while it’s trying to unfollow? Maybe your proxy was too slow. I’d suggest you try changing the proxy of one of the accounts that got error 581, and see if the error disappears.
What’s the proxy rotation time? And how long is it down for when it rotates? Mine rotate every 5min and I see all sorts of errors when it is down if the JV tries to perform actions, but then it resumes normally once the proxy is up, so could be that.
581 error usually means that your proxy was slow at the point when the action was executed. Proxy’s response rate can be different from time to time and perhaps they were working better when you’ve tested them on different accounts.