✦: Has your own interpretation changed from when you first began playing the character?
I don't think my interpretation of GD has ever changed consciously. There's been subtle shifts like his dialogue becoming more consistent and his vocal tics easier to identify and carry, but that comes with getting used to the character and writing him outside of the initial awkward and janky initial phase of writing.
Considering my outlook on writing is putting consistency of how a character sounds and acts like above all else, that's a good thing. If he ever seems to change, I strive to make it a realistic change through character development than something that just happens.
✎: What do you wish the author would reveal/had revealed about your muse?
More details regarding why Jhin is the way he is. Their excuse of a "mysterious backstory makes him scarier" is absolute bullshit and complete avoidance of the subject, presumably because Riot does not know how or does not want to protray the development of his psychosis realistically. Yes, this is a fantasy world, but come on. You really want to tell me the boy was born that crazy and be done with it? Christ's sakes.
I've personally rectified the matter in my own headcanon with additions like her and I hope to go in the full breadth of GD's backstory someday, but I want to keep the backstory reveals organic which is why I haven't written some end-all-be-all backstory, and likely never will.