I can't tell if it's Riot being super lazy and hoping that people won't be super vocal about it so they can get away with such lazy work on the ability effects, or if they actually plan to fix everything in the two weeks they've got until he goes live on the normal servers.
The sad thing is, they could do a blue/purple effect to his skills and it would match both Dragon Knight and Lord, which would give all of his skins a different model than his base.
I'm happy that Infernal looks so good but it's beyond disappointing to see none of his other skills get ANYTHING (aside from Pentakill which literally only got the exact same effects as Infernal).
Fingers crossed that the community will make a big enough ruckus about it like they did for Kayle and Morgana to actually get them to change it.