That's a quirk of Amidst. It only uses the first pass software when it comes to calculating spawn point and will pick 0,0 if no suitable point is found quickly. Minecraft later will refine this if spawn is far from land it will move it. Although if the ocean is big enough even that will fail once in a while
If you actually create that world in Large Biomes you will spawn on a forested island northwest of 0,0 at -699,-300 with one of the strongholds under that island.
The jungle temple really is there at 1136,1088 and when I teleported above it it had four pigs stranded on top of it. (using v1.8.2pre1)
Just checked the jungle/mushroom one in 1.11.2 via Amidst, and there was a stronghold really close to an ocean monument. Really cool. Gold, plus a way to the End, all in the same biome. Too cool.