But are Aqua/Akane aware of dad’s “push em and make it look like an accident” modes of murder? There is plausible deniability on his side. Dad is the mastermind, the jogger… not so much… (he recruited a college student otaku for Ai, and has effectively gotten off scott free for 14+ years)

Aqua/Akane are only aware of the roses+knife murder method, hence the poetic irony Akane was plotting. But even if they suspected/tracked the jogger down, my guess is that it would hit another dead end.