Notifying you with more than a generic message of "Thank you, we'll look into it" simply wont be possible for pirvacy reasons - not even if they dont notify you against who they're taking action (because if you've only reported one person, you'll know anyways).

Its not that I dont get the frustration, but I cant really see how they could inform people about what happend to their reports without violating the privacy of those who you reported. And you might say that they dont need to protect the privacy of someone whos breaking the rules, but I suppose we all know that thats a slippery legal issue and data they just cant disclose.

So, I really dont see what else is there to do than reporting and trusting them to look into it and take appropriate steps - I know its hard to do that when you see bots running around that you reported over and over again. But would it really be easier if they messaged you to tell you that they investigated, didnt had enough evidence and dropped the case?
I just dont know... either you trust them, that they're doing their job even without giving you a full report - or you dont. But if you dont trust them, because you're still seeing bots running around, I'm not sure if that would get any better if they'd straight out told you "Yep, we didnt ban that person".