Too bad Goth-lolita will never learn how much she screwed everyone over by failing to learn the lesson of "don't dish it out if you can't take if"
Not really. The moment Dino threatened Aria's master, Aria saw the whole guild as her enemy and planned to eliminate them.
The silly thing about Keela is that she could never take it; in her first meeting with Aria, her sneak attack got countered even though she was stronger than Aria then - basically, despite her better stats she had always been careless. She also sent Gai and Rhada after Aria, both had greater prowess than her and both disappeared - so she's a moron.
And then there's Dino, who failed to rein Keela in; despite the rules of the guild clearly stating that aggression against another member isn't tolerated and Keela showing that aggression right in front of him, he let it go without any punishment and instead told Aria to stop responding to Keela's aggression (so, "just take it and do nothing"). Considering that Gai and Rhada both went to kill Aria, that rule is clearly not one they ever cared to enforce.
So the one who really screwed everyone over is Dino; though to be fair to him, it's not like anyone would expect Aria to be that dangerous. He's been trying to monitor her, and even in this chapter he's showing he is considering how strong she's getting, but honestly, he should have gotten the memo from that very first person he sent to monitor Aria and her master's movements never coming back to report. Unfortunately, he really wanted to have something on Serjura, Aria's master, so he's been keeping Aria while he still thinks he could control her. He miscalculated.