As this dungeon will go away once the event will end, why don’t you keep it in the game in a different form?
Since fractals are “windows” on different fragments of reality, sometime well definite in time and space (Urban Battlegrounds Fractal is part of the flame legion assault on a ascalionian city), other times not (Cliffside Fractal is in a indefinite location, with a indefinite enemy and an indefinite giant to save
), why don’t you open a “window” on a Molten Weapons Factory?
The istance is well designed, should be a waste if totally removed from the game.
Maybe the current version is now a bit too long for a fractal, but you can cut a part or two to make it “fractable” (for example cut from the drilling part to the Thermal Core part and the final escape), remove Rox and Braham and balance a encounter or two (like adding a middle fractal boss). As far as we know there are plenty of this weapons facilities: the one in the fractal could be a dormant one escaped from the destruction or a early prototype one (so the copy-paste effect will be avoided/mitigated).
In this way the fractal could be at the same time different and similar to the one we are knowing during the event.
(sorry for my poor english
)