I was a freelance translator and a translation project manager for several years and can tell you there is definitely no app or software that can do what the patron wants. Not well, anyways.
Several apps do scan documents to create PDFs from camera images (Adobe has one). But if the patron wants to have the file translated, he will have to OCR it, and throw the text into a machine translation program such as Google Translate. The translation output will undoubtedly be a mess, especially for a complex legal document. If the patron goes that route, I would recommend he hire a translator to edit the machine translation, especially if the translation is intended for official/legal use.
Let me know if you need any more information about translation or finding a freelance translator for Spanish>English.