I would say Julian never had much of a chance to figure out who Jadzia really was with her joined Trill background. While she was trained to cope with the multiple personalities and lives of Dax, Julian just basically turns up on DS9 fresh faced and wide eyed and stumbles upon a woman he finds attractive. Dax got a bit lucky in having Sisko as her commander, as without him she may have had a tougher time adapting as she would have all this knowledge but still keep a lower rank and have to work her way up the ranks rather than taking on the Curzon father figure she took with Sisko. No wonder Julian is confused, sometimes she's a flirty female, sometimes she's an elderly mentor to the station captain and sometimes a Klingon warrior. Jadzia kept a lot to herself in regards to her past but Ezri was much more vocal in her troubles and Julian could actually figure out Ezri since she was much easier to understand.