Correction: The article does not state that the polar ice caps were immediately melted, but rather that they will nearly melt eventually. This is significantly different.
Actually, the article states that "We are facing almost full polar cap meltdown" which does not indicate time either way - however, later in the article you read "we expect sea level to have risen, covering at least two thirds of the existing landmass, the remaining surface being largely scorched", which is past tense, indicating that this has already occurred.
Strictly speaking, a crater should still be created through immediate heating of the ground directly beneath the explosion. It may not be as large as you would expect from a direct kinetic impact, but it would still be there.
I think that that would reasonably fall under "scorched". In any case, this is an argument from absence of perfect evidence, which is invalid. Especially when the articles explicitly state that it was an Avatar's doomsday weapon.
They are non-canon to Disney's continuity; they are still canon to the EU/Legends continuity.
To me, it makes sense to use a source which is acknowledged as canon on all levels, rather than pick a source from one line of canon. Star Trek also has a non-canonical/semi-canonical line of books that portray those ships as being much more powerful, but I reject that, too.
Check your math: 200x1012 tons is 200 teratons, not 200,000. The Venator's main battery is outputting more firepower than a doomsday every second.
Sorry about that math failure. Show's why I shouldn't calculate while groggy. Again, however, I still have to reject that figure from the EU. Not just because the EU is non-canon, but also because there are wildly varying depictions of firepower in the EU, and a figure that high completely disagrees with depictions seen in the movies. For example, in the battle over Coruscant, you see un-shielded ships taking turbolaser fire and not disintegrating into chunks.
Also, there is the slightly eye-rolling nature of building a Death Star if an outdated 20-year-old starship can accomplish the same thing.
Even by reducing these values by a commensurate amount to correct for the earlier math failure - to 0.88 teratons/sec and 4.4 teratons/sec respectively - we run into another problem: There is no evidence of damage output this high - or that our craft are capable of supporting weapons output in this range. If this were accurate, our orbital bombardments should be catastrophic, battle-ending affairs which would incinerate battlefields.
Actually, if you read some of the lore, you find lots of evidence for it. Planetary bombardment for DUST actually does require special rounds - probably powered down rounds for precision strikes. And they're using small ammo, for frigates. When the Amarr decided to destroy the Starkmanir, they simply hit the planet with tachyon lasers, which essentially glassed the surface. According to EvElopedia, the planet's crust was rendered, the tectonic plates shattered, and the planet flows with rivers of magma.
Similarly, unless a titan's superweapon would destroy a planet, there was no reason for Heth to park a ship like the Leviathan in orbit. Go through the lore, and you can find quite a few depictions of massive damage being done. It's also the only reason I can think of for Caldari dreadnoughts in TEA to use plasma beams to bombard Gallente forces - citadel missiles would have destroyed everything around. As it is, Caldari dreadnoughts are perfectly capable of destroying entire populations if they want, as Tibus Heth uses that threat against Fouritain.