Hello,
List of browsers that theme fully supports you can find in theme description https://themeforest.net/item/xstore-responsive-woocommerce-theme/15780546
Old browsers could give the errors because of using CSS styles that are up to date but if we want to be top notch in we can’t use out of date styles to support out of date browsers. Unfortunately, we can’t even test theme in such old browsers because don’t have old devices.
Regards