sounds like just "treasure troves". Not singular coins. But I bet if you went turning in your junk and individual coins as Showtime jokes about, or "seeking clarifications" that loco-digger suggests, that it would only be a matter of time before the revoke the permit entirely. And just make it simple and say "no md'ing". The psychology of taking up their time to answer Q's, just makes it "perpetually on their radar" as something they have to deal with. This is why there are many stories circulating of permit-programs rescinded, and md'ing banned at some point. Because the mere fact that a "permit" exists, means it's perpetually on their annual list of things to consider, think about, etc.. And then sure as sh$t, one year they decide "gee, do we really want all these yahoos out there digging up the parks ?"
And also notice your permit language says you can't dig deeper than 6". Really ? Ok, so I guess that means they have a fellow follow you and I around with a ruler measuring the depth of the coins/targets you dig. Right ? And he cuffs you and hauls you off when you go deeper than 6", eh ? If I were getting a screaming signal on my machine at 6" , telling me a silver dime is just a tad further, do you think I'm going to stop ? Heck, there are park turf scenarios where I deliberately PASS any signal LESS than 6" (in the quest for deeper older coins, trying to pass clad).
Thus while the notion of "permits" seems to "wax romantic" in the eyes of md'rs (thinking it's a carte-blanche to detect nilly willy), yet as your permit shows, they are ALWAYS fraught with problems and silly-ness. Hence much better for the law to be silent on the subject, not addressed either way.