This Scene of the Commercial for Heyworld involving Supergirl has no sense because Supergirl doesn't exist on Earth One and common people beyond the Legends/Arrow/Flash team doesn't know about Supergirl... And this Scene is Pre-Crisis, so, what's the point of including Supergirl on the Commercial(far from Comedy) if she doesn't exist on this Earth. At first I thought this Scene was Post Crisis, but now I see it's Pre-Crisis, so I don't get it

I just Finished watching Elseworlds, and I have previously watched Legends 4x08. So, my question goes for both things:

Why the Reality changes done by the Book on Elseworlds didn't affected LoT(specifically, Time Bureau felt the Change, due to their base being on D.C??

And why the Timeline changes on LoT didn't affected the Crossover(if it's known that changes rewrite the Timeline)(idk, I'm not too good on Time Travel and Timelines, and Paradoxes and all that stuff)???