I have allowed on Checkout page returning customers to login, but one text is not translated even though it is translated in the woocommerce (checked via loco translate and also WooCommerce is 100% translated for my language)
Checkout is the Woocommerce template, you should search the string in Loco > Plugins > Woocommerce. Our theme does not have the strings for Woocommerce templates.
Please check the checkout on one of the Storefront theme to understand if our theme causes the problem. If you see the same on the Storefront, please refer the Woocommerce forum. If this problem appears only on our theme, please provide the site admin access for us to check.