You want to go with Interdream to highlight the new direction this fangame has gone? Okay. But what's up with keeping the Deltarune name around and slapping Interdream on top of it like the fangames that call themselves UT Prequels? That makes the name change unnecessarily long and a mouthful compared to the "Deltatraveler" name and it seems like that you are only following a Pokémon-like stereotype for the sake of it without giving it much thought.
There's no point in keeping the Deltarune name around. Interdream is all your fangame needs identity-wise.