Add language tag to a website + custom code for product page

I am currently working on a Squarespace multilingual website (French, English) for a fashion brand. I would like a language tag to be installed on this website so that when French users go on my website, and order or subscribe to the newsletter for example, they receive notification confirmation emails in the language of the website they are navigating on. Currently, Squarespace only gives the option to have the confirmation emails to customers in one language. I would like the following confirmation emails to be translated into French: -Order confirmation email -Shipping order confirmation email -Payment declined confirmation email -Reimbursement confirmation email -Confirmation email subscription to the newsletter Confirmation email product not available anymore In addition, I installed a third-party system on my computer to translate all my website into French. In the commerce, in the product page, I am unable to change the sizes in the French version of the website. I would like them to appear as French sizes (38, 40, 42...) instead of American sizes (2, 4, 6...) Do you think you would have enough expertise to work on the custom code?