As I see it, it's highly implied that Laika's parents created the Cosmofs to help their ailing daughter, which is comprehensible, but her mother dying in an accident should have tipped them off that such creatures were dangerous. Then we have Laika and Imori who turned out to have known perfectly well how dangerous those vermin were and how important was Laika for their wellbeing. Yet they leave Laika's daughter to contain what was potentially a world ending scenario with no explanation or training whatsoever, they leave an emotionally vulnerable child, probably knowing fully well how terrible the future was going to be.
Mind you, they try to pass off the Cosmofs as a minor issue, but they're not cute mischievous critters. They're a mutating plague that has caused chaos and devastation all over the world, which has resulted in casualties. Mira has all the right to want blood. It's not a matter of "we can undo this tragedy". Even if time travel shenanigans somehow bring back all the dead back to life, it won't erase the fact that Laika's neglect caused a catastrophe. They're trying to cleverly put this issue aside with cheap emotional manipulation and shounen stock phrases like "I'll protect my family", but the fact remains that whatever the kid Laika was back then, she screwed up big time, and at the very least, Alice should feel a wee bit conflicted in defending her, instead of lashing against the world for rightfully blaming her mother for the disaster.