La Celestina

The last week I had an exam of a book that will be in Selectivitat. The book is La Celestina.
I think that the plot is good and interesting but the edition that I had read it was very difficult to understand. Why? I say this because the vocabulary that is on the book isn't very up-to-date, and the ortography was worse. I tried to read it but when I had like 30 pages readen, I didn't understand anything.
I know that the book is very old, but if they do a new edition, they have should have writted the book to the people that doesn't understand that vocabulary.