1 Amidala: You’re making fun of me!
1 Anakin: Oh, no, I’d be much too frightened to tease a senator.
2 Amidala: You do know that senators are regular citizens who should be approachable and sympathetic?
3 Amidala: Fear of the government is a sign of a failing system.
4 Anakin: Okay. I was making fun of you.
4 Amidala: Security!! {armed clone troopers appear behind her}

I ran a text search through past comics to find any instances of Padmé speaking, so I could copy the speech balloon colour, but I was surprised that I couldn't find any. So I searched for some lines of dialogue which I thought she might have said in comes, and I found that when she appears her name has always been given in the transcript as "Amidala".

I wonder if it was because I didn't want to use the accented "é" character way back when I began.

Anyway, whatever the reason, it seems we're stuck with it now.