Hate to burst your bubble man, but there are a lot of illiterate people who know how to write their own name. Of course, Ariel is royalty, so you'd expect she can read. So, it could go either way?
The contract is in English from the point of view of the viewer just like Disney's Aladdin is heard in english but the characters would have been speaking their arabic. For all we know her contract was written in fish language but Disney kindly translated it for us non-fish speakers.
She didnt read it she musty signed her name. But everyone in the movies spike English and Eric was am English Prince so...she was probably used tip speaking it. The dont wrote a lot underwater I dont think....but she was a princess so she would know how to write her name.
The point of the post is that Ariel couldnt speak to Eric and tell him what was up with her, what she wanted or anything because she had no voice. The post implies that she could have just written it to him
I think she didn't write down the explanation because Eric only recognized her singing voice. He hadn't seen her, so he probably wouldn't have believed her. He was hesitant towards falling in love with her because he kept thinking of the girl with the beautiful voice.
Sorry swipe makes fools of us all