Those are all actually used fanworks. Especially and unfortunately the infamous "sexual deviant" one. Thus they are not canon as it should be.

Fan works shouldn't be used to judge a character, seeing as canon Celestia is probably too good for their mortal world. She's an utter sweetheart.

Fan works only ever get brought up because Luna is a waste of space and they don't want to believe their beloved princess of the night is so useless that Celestia did her one job for a millennium.

Yeah, though I personally see Celestia (and the other two Non-Twilight princesses) as having a fairly bland character despite the varying depths and backstories that can be worked with. Celestia is a benevolent ruler that fancies a little good natured humor at the expense of her subjects while keeping her primary agents in the dark about much of the finer points in he history of her kingdom for various reasons, Luna is the story of a woman haunted by her past and is on a road of redemption while she hopes to never go back to that old self, and Cadance is a great mentor and precursor for Twilight, as she also was given her role as a princess upon achieving demigodhood from achieving mastery and enlightenment in a particular field of study.

Though when Klonoahedgehog said "Dear Celestia You Suck," my mind immediately thought of Celestia's platter of non-canon personalities ranging from troll to dictator. Sorry. :o

Fair enough if you see Celestia bland.

After a year and a half of putting up with this "Celestia is evil" bullshit, despite canon Celestia probably being thing nicest being in any universe ever, I'm done brushing it off.

If Luna ever expressed any regret beyond her "I'm sorry!" in episode 2, I'd believe that's her story, but it's clearly not.

This.

Shots fired.

Yeah, I'm sorry for bringing it up and I will refrain from doing so again.

And I never said that Luna's character was all about her regrets as Nightmare Moon, but rather that the angle for that is there but never delved into, leading to a rather pointless backstory.
Hopefully the Season 4 episode that has Twilight witness Luna's corruption will somehow work with that, along with explaining how a solar deity managed to govern both night and day for a millennium without any problems.

Regardless, Luna and Cadance need to receive mail sometimes.

Celestia received mail by mandate to Twilight and, later, the Mane 6 (And Spike). Twilight wasn't doing it for fun, it was part of her assignments.

I don't know about you, but I'd like to receive mail from another organism with whom I share a connection no matter the circumstance.

Come to think of it, wasn't one of the main reason she went rogue (before it was retconned into the Nightmare Force) because she felt neglected and feared by the world?

Yeah, she needs more love and recognition beyond a yearly festival that reminds her of what she did 1000 years ago. Even if the festival is now about harmless jump scares and practical jokes.