Hey there, @Kalanit
Apologies for the delay in response, I was out of office for the week. Please note that tagging Shopify Staff members who have not participated in your topic for example is not an acceptable use of the Mention feature so the Mentions may be removed via an Edit. This is outlined in our Code of Conduct here.
I was able to check in with our themes team regarding this issue. At this time translating the Buy It Now button is not supported as it is a dynamic button - that is a button that changes based on the user's habits. Most of your visitors actually will not even see the Buy It Now button. I took a look into this and found that the dynamic checkout buttons appear based on a number of things, most importantly the user's browser. So, when you are looking at the button in the theme customizer you are looking at it as though you have no cache, whereas when you look at your site on a regular browser it appears as a PayPal button as you have logged into PayPal on your browser previously. For your customer, the button that is most relevant to their online habits will show so if I were to look at your site from Safari on my iPhone I would see the option for Apple Pay. You can read up more on our accelerated checkouts here. I hope this makes sense, if you have any further questions please do let me know!
All the Best,