Let’s say you have a PDF file with 380 pages, all scanned images.
The first task is to split the document into lots of 50-page documents. You can use:
https://www.ilovepdf.com/split_pdf#split,range
Now, you will have a 6-pages document.
The second task is to OCR the 6 documents, using:
https://www.ilovepdf.com/ocr-pdf
Join the PDFs into one using:
https://www.ilovepdf.com/merge_pdf
The fourth task is to upload and then open the PDF in Google Docs:
https://docs.google.com/
Finally, open the Google Doc and translate the Google Docs into another language.
The only downside? You generally get a poor-quality translation.
The OCR, also, can lack quality.