We have a similar problem - the “Buy Now” button doesn’t translate automatically to Slovak.
We had this issue in the past and you were able to translate the button on your end but since a few weeks it’s back to English, not sure why.
Example: https://pokepopspot.com/sk/products/pokemon-scarlet-violet-151-booster-pack-english
“Buy Now” in Slovak should say: Kúpiť