Whatever, the animations would still be better.
I don't think you quite understand how engines work, they don't automatically make things better they are still reliant on developer ability and the materials they are using.
Putting Irnia directly into Unity wouldn't change anything. It would still be using the same assets by the same artist and coded by the same developer.
Like moving games from RPGM to Ren'py. It doesn't improve anything, nothing at all changes it just removes the walking. Everything else is still the same.
It would take a whole new set of assets to change animations which would cost more money for a game that doesn't bring in all that much it wouldn't be worth it. The dev would be out of pocket.