Fairy Tail: Erza Scarlet or Elsa Scarlet!?

the answer

The real name is 《Elza Scarlet》
because the volume 12,the name is written on her gravestone while she tried to controll Aetherion.
Japanese doesn`t have differences ‘R‘ and `L`.Usually it transforms `R`,but sometimes it is correct to transform `L`,which the name or meaning.
I think the translator had a mistake.

In one of the first episodes when she fights Natsu you can see a board where it says Elsa and Natsu