The accounts are all linked together created on the same day (November 28, 2018) and their comments are separated by minutes without any identical reply (yet) that's to say they aren't bot but alt accounts operated by an individual created just for bumping the Bounty thread of GRABITY
I believe Grabity could have a hand in this since as you said you have reported previous offend from same bounty thread. Maybe the bounty thread should be locked or something...
By the time a Newbie reaches 1000+ posts without earning a single Merit, it's pretty clear he doesn't contribute anything to this forum.
I'll list all accounts that posted in that topic (the number before the username is their number of posts in that topic)
This is just to show you how toxic the thread is, like I said something should be done about thread and alt accounts spamming forum through bumping the bounty thread.