Actually, Ohma did mention in an earlier chapter that under training with the Kure Clan, he's fought with Raian on a daily basis almost. And his loss tally is higher than his wins tally against the demon. That would indicate that he's somewhere close to that level, maybe not higher. Kanoh might be around that level as well, if not higher. Though I honestly find it hard to believe that anyone on that roster could beat Removal Raian using the full-range of his Kure techniques.
Also, Kuroki mentioning that Arashiyama might be on the same level as him could mean something different from what we're perceiving from those words. For example, Kuroki could be talking about the latter being on the same footing as him in terms of mastering his martial art. Like the apex of judo and the apex of karate. But the swing is still largely dependent on the opponent wearing a gi. Most fighters on the Kengan side fight without their tops, or wear skin-tight tops (like Kanoh), making it difficult to implement the swing. We don't know if Arashiyama can display the same level of potency or strength when fighting against different techniques, or other forms of martial arts as well.