I mean Navani says that Shadesmar is easily reached through the Oathgates, so... something happened and now the Oathgate spren are allowing them to travel.
But I don't know if he can travel through his own perpendicularity.
Someone hypothesized that Dalinar might be able to unlock the Oathgates as the de-facto Honor, and it seems to be right, if they can now use the Oathgates to go into Shadesmar.
Truth whispers back, "This is just a backup plan. I am not planning on attacking Jaxevist. Also, we can not simply leave the holed here. There are things going on that we don't know much about."
Why won't it have one? I am possibly misunderstanding you but I don't understand why you feel that a Kalad's Phantom won't have an Atium shadow. What about it would prevent one from forming?