Why does Talia call Batman "beloved"? Is he the only person she calls this way or is there someone else? You could say in which comics?
I think Talia calls Bruce ‘Beloved’ because ‘Beloved’ is the direct translation of ‘Habibi’ in Arabic and that would also explain her (and Damian’s) formal manner of speaking, because of the structural difference between the two languages.
She only calls Bruce and Damian ‘Beloved’, obviously because they are the only ones who she’s ever truly cared about. And her father, but her relationship with Ra’s is very complicated, and not as intimate as with Bruce and Damian.
As for in which comics, well, basically almost in every comic she has interaction with Bruce. Just recently, she called him ‘Beloved’ in Dark Days - The Casting (2017).