Mio is talented and seemingly confident, why did they lost? The problem isn't(only) in Aine.
I think Mio should slightly adjust her world-view. An idol is a star, she shines over the fans with her brilliance. An idol guides people and gives them smiles. Mio's world, however, is centered on LMT. She starts with looking at them, gets overshadowed and blinded by their radiation, only after that Mio looks at herself and doesn't see her own light anymore. The order here is crucial. Mio should be the center of her own world. Mio's first and main job is to discover her and PP's radiance and share it with their fans. And only then, after reaching their full potential, it's time to compare to LMT without risking anything.
Aine can help Mio here by shifting Mio's attention from LMT to her and PP.