The verses I knew the song were these 2 "you are my sunshine" followed by "the other night dear". I originally thought the song was about a mother who watched her son go off to war in the first verse begging him not to go. Then the second verse is her much later waking up from a dream where she was hugging him, but reality of him having died in war and never coming back caused her to break down and weep.
The test wasn't really for all of them, it's just for Akira. She already knows a lot about him and his powers, but thinks that all power corrupts, and just wants show it even to Akira himself that he's also capable of being corrupted by that power.
She also knows that Aria is protecting Akira and thinks that this power was bestowed to him by Aria, so she also wants to show her that she's a danger to this world.
I guess the moment mommy Aria said something like "you try hurting muh boi again, you ded", it becomes clear no matter how fcked up our boi condition is during that battle......he WILL still be fine somehow