I'm not sure what a picture of a Timothy Zahn book has to do with anything. Is that part of the Disney canon now? I'm less interested in the EUs than in the primary evidence of the films. The previous EU had several brainbugs based on superficial readings of the films, and I suspect the new one will, too.
As for being a senator and having "soft skills," I think you overestimate the skill overlap, and make assumptions about the skills late Imperial Senators actually had. Leia's only apparent qualification to sit in the Senate is her royal station. Given the rather swift dissolution of the Senate, it seems none of the other senators brought anything especially vital to the Empire, either. Even if there is a significant overlap of skills, having the skills to be a diplomat does not make one a diplomat.
Looking at the movies, and not the misinterpretations of Lucasfilm Licensing, Ballantine, Del Rey, West End Games, Wizards of the Coast, or whoever hands out the writing assignments these days--is Leia a diplomat? Is she a member of the Imperial, Alderaanian, or Rebellion ministry of state? Does she officially represent one sovereign state to another? Does she overtly collect information from a foreign state? Does she provide consular services to citizens who find themselves on foreign soil? Does she claim, or exercise, diplomatic immunity?