Not that I know... So just speculating. I would not be surprised if much of that money was paid to 'themselves' (Blankenship's and Laginas") The TV production company has been billed by the corporation that owns the land (Blakenships and Laginas) for a significant portion of that amount. This is money is paid from all the sponsorship, government grants etc. I doub't much of that money went to external parties (I imagine Fred Nolans family are now getting some for letting Laginas search their land). Given that Laginas are basically selling the rights to themselves they can charge whatever they want to milk out all the money the TV show makes.
As you said they already owned most of the land...
As to where the 15 million you are quoting comes from and what it is meant to include is another matter. They seem to be wasting millions. In the past they claimed that each hole cost over a million to dig. The explosive/sonic mapping was over a million. I imagine the cost of putting up the coffer dam and taking it down again would be expensive as well.
So they have dug 2 new big holes this season alone.. This plus the sonic map and coffer dam already must of cost them in excess of $4 million.
The treasure they would have if they spent the 15 million on gold
Here is a picture of about $1.25 million in gold bars so juts picture a pile of 12 times the amount of gold shown...
View attachment 1693841
If you are correct and that is only for the rights then the whole amount they have spent is probably closer to double that.
Now that is a TREASURE....