Manually translate front end strings of text

Hello,

I have translated my website into french using BradGood's method and code. Everything works fine except the checkout (obviously, as I know it is not really possible to modify this one).

However, I am certain about being able to modify some of the shop's front end strings of text, to have a more seamless experience in french. 

For example, on this product (https://gregoirepansu.com/fr/tirages-dart/p/chemin-sinueux), in the french version of the website, the price still states "from XX€" instead of "A partir de XX€", "Size" instead of "Format" etc...

I have already translated a string of text in the email address box by example, with this code :

    if (lang == "fr") {
  $('.email input').attr('placeholder','Adresse email');
      }

I also translated the "add to cart button" using the same code. (Even though it goes back to "add to cart" after you click it once).

Is there any way for me to target those strings of text and translate them ? By example, targeting in French any "size" word and translate it to "Format" ? 

Thank you so much !