That is a completely different red and a completely different sort of red. Bear with me while I explain.
At both Mdina and MDG, brown glass was produced by the addition of silver nitrate to red glass, (in a similar way to the yellows and greens being produced by the addition of silver chloride to clear and blue glass.
Silver nitrate does not, as far as I know, melt in the way silver chloride does.
It's a gritty black powder that burns everything it comes into contact with, and it soaks up water from the air. I still have an old lab coat I kept for using silver nitrate
exclusively - it's full of tiny holes and burnt brown spots.
Both silver salts are very expensive. (the chloride or the nitrate are called salts in chemistry.)
with Mdina - I do not think silver nitrate or silver chloride were used in the more mass production sorts of things. They were, of course, used in the paperweights which are in the Eathtones pattern.
In the boat thing you're showing there, it is a bought-in standard red enamel that has been used, not the reds that you see along with the browns in the streaky bits of Earthtones from both factories.
It's not a red that is left behind after its "browning" with silver.