It's most likely going to be edited in the future once more knowledge is brought to light on it or when they feel like it's appropriate to.

He dint use his dojutsu on then he teleported then inside the cube via space~time ninjutsu

Those aren’t normal cubes it aloud them to live in there without aging a day

Daikokuten is the justu and the name of the dimension, like Kamui. Kawaki did not use the jutsu to send them into that dimension, he used a Kāma rift.

That’s wat I was tryna say 💀

^^once again the previous panel: A shinjutsu daikokuten

The shinjutsu grants access to that dimension. The warp is also named the same as that dimension. He used the Kāma to send them to the dimension he had access to because of the shinjutsu.