Eh unless you’ve got additional information otherwise, I’ve seen several references that are very well in favor of the 51st episode being the basis for AO.
Like Tenchi you have to dig a bit deeper, in that the 7 fragments of Eureka are her scattering across dimensions and time. Which is why Renton (20 something ver.) is out trying to track her down at the end of AO season 1.
It was also said somewhere in there that Ryoko couldn’t leave in her astral form to move away from the cave. She was very constrained.
As to school… we Tenchi often felt comfortable by the cave, in the flashbacks Ryoko has later of her watching over him, he has a school uniform and bag. Pretty easy to assume he came there and did homework, reflected, cried mommy, etc.
It was a stasis/prison… if memory serves she was pretty much “dehydrated” from her energy and outside sources after Yosho took her last gem.
She could float around after a very long time in her astral form because she collected a little energy, but not do anything else. Tenchi had to break the seal.
