Can anyone here speak/read japanese? I think it might be a good idea to check mod section the japanese minecraft forums, they might have some interesting stuff, it can be either amazingly great or very weird
Inventory pets changed the dirt screen to 'your pets said goodbye' if i'm not mistaken, so maybe thats possible. But that dirt screen only show up for a couple seconds for me.
I think twilight biomes spawning in the overworld is caused by minecraft considering biomes with id above 128 as a sub biome, changing it to a number below 128 should work