It relies on tesseract for its OCR (https://ocrmypdf.readthedocs.io/en/latest/languages.html), so you need tesseract's language packs (http://tttthis.com/blog/convert-image-to-text-tesseract-ocr) to do other languages.
"OCRmyPDF that will add a text layer to a scanned PDF making it searchable"
FOSS
sudo apt-get install ocrmypdf
ocrmypdf input.pdf output.pdf
SPANISH (characters, otherwise it won't be able to copy-paste ¿)
ocrmypdf -l spa input.pdf output-spa.pdf