Indeed, once you start looking at it things start to break down & there is too much setting specific stuff attached that the breakdown is just painful.There's a lot here to unpack... The idea that Godzilla is Japan's Barney is so entertaining that it is a must to meditate upon. On the flipside, OTOH, that Barney is America's Godzilla is enough to make Baby Jesus™ cry.
And, no, it was Gamera that was a friend to children everywhere (IIRC).
I do love me some kaiju.
As to the silly khyber is eberron's "The Abyss"... This is what is in The Abyss is & a summary of what it contains. Eberron has a different role for demons than the settings that use The Abyss... That role is so different that the word "demon" in the context of eberron includes devils as both are children of khyber, busy with other stuff, & not in need of souls for the same (if any) reasons as in settings with The Abyss. All of that combined makes it silly to suggest that Khyber contains the river of blood/river styx since those are specific lore knots tied to the workings of demons that don't fit eberron. It's made more complicated because Khyber is not well mapped & many of the well mapped layers that exist within The Abyss conflict with stand alone planes within eberron's cosmology (risia/Shavarath/etc). It's certainly not helped that the demonlord/king/prince/etc of those layers of The Abyss are deeply tied into the lore of a setting that hinges on that incompatible role for the Children of Khyber. Many of those problems are even worse if you replace The Abyss with "The Nine Hells".