Professional plan of app allows you to translate FAQs along with other content. Note that this app has its own translation feature so you don't need any other translation app to translate FAQs.
FAQs:
Once you are on FAQs edit page, you would see available store languages in a dropdown to select from. Simply update translation for your content and save the FAQ.
Categories:
Once you are on Categories edit page, you would see available store languages in a dropdown to select from. Simply update translation for your content and save the category.
Translation for other content:
Translation feature is also available for other content like intro text, footer text etc., Once you are at appropriate area, you would find a button which would allow you to add translation.
If you publish new language through your Shopify admin, you won't see that language in app right away. You would need to do a manual sync as explained in following article: