1. At the time of the statement, everything in existence referred to the World (Militia World) as Anos didn't know about the Bubble or the Silver Sea. (When the Statement was used) "Everything in existence"=World.
2. Venuzdonoa has worked in Deeper Worlds just fine. But a Deeper World would still be "everything in existence" as Anos referred to in his statement, because he only had knowledge of the World.
3. The Silver Sea and the Worlds in the Silver Sea are two different things. Worlds (referred to as "everything in existence" when Anos made that statement) can't even survive in the Silver Sea without being surrounded by Bubbles which protect them from the Silver Sea's environment (constantly drains magical energy). Why are you equating Worlds in the Silver Sea to the Silver Sea itself?
Anos' magic as well as his power are not limited to the bubbles but to the silver sea, it is easily shown when the incident of the vortex that was catalogued as a threat to the silver sea, and let's not forget that Venuzdonoa still has the power of Anos' Eyes and not only the order of destruction and the power of Anos' Eyes even in the silver sea Anos is afraid to use it because of its destructive power compressed into a bottomless abyss.
4. Venuzdonoa hasn't proven that it can destroy the entire Silver Sea.
Where's the needed of end the series? The same thing happened with Venuzdonoa destroying Nousgalia, if order is destroyed then everything will be, that's why Anos had to revive Nousgalia, destroying the silver sea would be = end of the series, Anos doesn't want that. And already the mere fact of destroying the order is to affect the order that flows throughout the silver sea mainly the main orders of the silver sea. And we already know that if the order is destroyed = end of everything.
No.
I'm claiming that your specific interpretation of Parrington's statement shouldn't be treated as fact when no other feats in the series supports this.
The fact comes from their nature as lions of destruction my friend, what would be the meaning of parrigton as a lion of destruction claim such a thing? Even he went out of his way to destroy Anos because he knew his claim was true but Anos was more than he could handle and he was destroyed. And as I said before, the claims come from users who have the power to manipulate and determine fate, so you are downplaying their ability.
As I've previously said, I lack knowledge of the verse, but what feats to Anos and MEoCD have regarding scaling to the Silver Sea?
Lions of destruction when their power is awakened will be enough to destroy the silver sea, especially Anos who has not even shown his full power yet, MeoCD being able to destroy a threat categorized as a threat to even silver with only a fraction of its power and Venuz having the power of Anos and MeoCD and continuing to destroy everything it has faced no matter how tough, eternal or infinite it is.
And again this is one of the most important things that OP can't even debunk
And already the mere fact of destroying the order is to affect the order that flows throughout the silver sea mainly the main orders of the silver sea. And we already know that if the order is destroyed = end of everything.
Also
The World's depth is the strength of the World's Order. It refers to the great influence the Small Worlds have on the Silver Sea. Magic power flows from the Shallow Layer to the Deep Layer, and the Order exerts its power from Shallow to Deep."
"According to the Order of the Silver Sea, magic power flows to the deep layer and the Order exerts its power to the depths.
All the silver sea is made of order, the order follows logic/reason, Anos, Venuz, MEoCD can destroy both order and reason, the order of the silver sea is not exempt of the reason, therefore it can be destroyed as well as all the orders that were destroyed and restored. The main point is that there is no need to destroy the silver sea going by the current plot of the series, but there is already a hint that it can be destroyed and there are current threats that can affect it.