Fixing Aetherytes was not previously one of the skills Otohiko possessed. At least not in so many words. But he was the one who passed through to his destination, and he's the only one there who can reactivate the destroyed crystal shard, so he's doing his best. It helps that it's just fixing rather than building; the foundation is already there, someone else has already laid the groundwork, now all he needs to do is get it back up to how it was until a moment ago.
Under the time constraint of "they mustn't let the Lady Iceheart escape". So that's fun.
Still, if anyone can do it it is he, and he does it.
