Its complicated, as is so often the case in real life. For all her weirdness, she is very narrow-minded on certain subjects, which can lead to racism or something quite close to that. Apart from her dislike of "elfy" things, her prejudices against Tevinter (though hardly unusual) can be considered racism like in real life.
I think most telling of her nature there is her reaction whenever someone suggests to help her learn more about elves or magic: She always gets very defensive and angry, even afraid of becoming more "like them". While she seems to be able to accept Solas or Dorian (or an Elf and/or Mage Inquisitor) individually, she clings to her prejudices about these groups as a whole, which is frankly quite common for real life racists.
At least in my opinion, having some prejudice against certain groups based on your personal experience is quite understandable. But someone who refuses to even attempt to understand these groups better is irrefutably racist to me. Or otherwise bigoted depending on the group in question. And Sera, quite frankly, qualifies, as much as I try to like her and find justifications in her quirky nature.