The strongest hero.

If Ashan leaves, Kha-Belekh will leave too.

Or Urgash might want him to leave. Besides, something might happen to him, just like it happened to other Demon Lords (i.e., he might be deposed).

It wasn't him who reached Ash's consciousness; it was she who opened her consciousness to him. Ash helped him in this.

Yes, Ash opened her consciousness to him, but why? There was a man, and suddenly – you're already in Ash's consciousness? It seems that all sources clearly indicate that Sar-Elam was the first to "make contact" with Ash: "Sar-Elam, the first mage, touches the consciousness of the Dragon of Order and learns the nature of matter and spirit and the highest path of power" - the quote is taken from this site. I'm saying that Ash didn't just make Sar-Elam the Seventh Dragon; he fully deserved it.

In terms of status, no one is equal to the Elemental Dragons except for the Elemental Dragons. Demon Lords are not primordial; they are just ordinary leaders of the Shio. If the Lords were dragons, Ashan wouldn't exist.

Perhaps you misunderstood me; by Elemental Dragons, I mean Elrath, the Dragon of Light, Silanna, the Dragon of Earth, etc.
Then it goes like this: Ash created these Dragons first, and Urgash, in turn, created the Demon Lords, the progenitors of the demon race. Of course, the Demon Lords may be weaker than the Dragons, but in terms of status, or, if you will, in terms of birthright, they are equal.

He couldn't have achieved this on his own; Ash was involved.

But Kha-Belekh's power also wouldn't have been possible without Urgash. However, the Overlord remained a Demon Lord, only becoming a full-fledged master of the Shio.