Hi,
You can indeed change that with a translation override.
However, you won't find the translation key in the translation file as the system searches for it and if not there it falls back to a generic translation with the name of the sorted element + ascending or descending.
I'm not sure what is the translation key you need. It depends on whether you're using the "product sort price" or the "price" for the sorting.
So it's either SORT_ASCENDING_PRICE or SORT_ASCENDING_PRODUCT_PRODUCT_SORT_PRICE that you want to use a translation override key when editing your language file via the HikaShop configuration page's Languages tab.