I think people forgot that the tragedy happened when Calliope was only 15, so saying that you want her to see as a 16-18 years old girl is impossible. If the timeskip showed her as a 16-18, it would be pointless. The tradegy would be skipped and the plotline would be ruined, so it's reasonable for her to be only 12 years old in the timeskip.
Although I can't wait for her to grow up too as well as the other characters hehe (=・ω・=)
I think people forgot that the tragedy happened when Calliope was only 15, so saying that you want her to see as a 16-18 years old girl is impossible. If the timeskip showed her as a 16-18, it would be pointless. The tradegy would be skipped and the plotline would be ruined, so it's reasonable for her to be only 12 years old in the timeskip.
Although I can't wait for her to grow up too as well as the other characters hehe (=・ω・=)