Button 'back to course' and 'Fill in Blank' problems

Hello, I have a multilanguage WPLMS courses made it with Polylang in 4 languages. The courses are free, same as units and exercises. Our first problem is when we finish a exercise in the page where shows the quiz completion message and the two buttons on the right side, the second one with value 'back to course' doesn't work because it not redirects to the associated course. It not works in all the languages, so we can't define what's the problem. Could you help us why is happening this? Is the problem about the form? It's about the Polylang pages? The second trouble is a 'Fill in blank' bug. We have a language Català that needs apostrophes because we are doing some grammar courses. When we fill the input with an apostroph (we think that others specials carachters will happen the same), the pages with the results shows these ones empty. We did that comprobation because if we do the same exercice without apostrophs, the results page shows the results correctly. We need to fix this because in the future we need to do courses in French that needs apostrophs too. Could you help us with this too? If you need it our webpage is http://www.deafli.com/nueva Thanks so much.