To support Diemonite22 on the manga panel issue, I'll present some pictures from the manga.
https://puu.sh/ycE6t.jpg
6 pages before the said picture, we see the "spear" up close. Arkham states that it's the seal of the Demon World. Meaning spear was there to separate two worlds or at least to assist this cause.
https://puu.sh/ycDTP.jpg
2 pages before the picture. Arkham states that there was a link between Heaven and Earth and it become unstable because of a war that Heaven was in.
The unstability of this said link caused the Underworld aka Demon World to born.
So Heaven or Earth =/= Demon World. This is important. In a way, they are all separate; but as stated here, Heaven was once tied to the Earth aka Human World.
https://puu.sh/ycEjZ.jpg
Just 1 page before. Arkham states that a demon "woke up to Justice" and used this spear to seal the Demon World. It is pretty obvious who that is, eh? He also mentions that the record on the object states some of the demons' names were "erased" as punishment.
https://puu.sh/ycuvs.jpg
Now to the debated page. The text says that "The demon hammered a giant spike to Earth, so it would never be split from Heaven again." In other words, The demon in the picture reconnected the Human World and Heaven that were once linked to each other by this spear/spike and he sealed the spike to ensure they will stay connected to each other.
Remember how the link between those two worlds getting weaker caused Underworld=Demon World to appear?
The black demon here is Sparda himself! He sealed the Demon World with hammering this spear. Need more proof?
https://puu.sh/ycEyF.jpg
Arkham himself says it was Sparda who erased the names of the demons there. I think it is pretty clear right now.
If it's still not enough just look at Sparda's model and compare him with the picture:
Also, scanlation clashes on some parts with the official translation; but this line is the exact same:
https://puu.sh/ycF2g.jpg
So yeah, I don't see why would Mundus seal Demon World with such a spear. I believe there's no doubt that the demon in that picture is Sparda.
This also proves official translation's viability.
There's more though. Arkham also says this:
https://puu.sh/ycEKW.jpg
"This statue is just a representation."
Which means if we take the "Twice he struck the Earth (...) and did not rend it." phrase from scanlation as official, it means this sentence wasn't a display of inability, but instead a compliment! By that Arkham means "He struck the spear to Earth twice and he thrusted it all the way in without even causing harm to Earth."
So if the scanlation is taken canon here, we should consider Sparda as at least 5-C with such a sheer force and precision that is able to pierce through a planet and not causing it to split apart.
Of course, this part is just pure speculation and I wouldn't advise to make any upgrades depending on that; but I believe this proves that some of the decisions were rushed in the previous thread. I rest my case.