I agree it might be a good idea to make the ‘cart’ feature optional as many of the other features are in this plugin, as it is a source of potential conflicts with other plugins.
This wouldn’t be too hard to do but not entirely sure what the impact would be – feel free to suggest it on https://github.com/hyyan/woo-poly-integration/issues.
>Generally get an empty basket if the language changes
I can’t reproduce this, however please note the current release version 1.4.3 is rather old, a draft release has been created here addressing primarily variable product and variation issues and JQuery updates (props @leemon):
https://github.com/hyyan/woo-poly-integration/releases/tag/1.4.5
If there are specific outstanding issues on the latest version please report in as much detail as possible on https://github.com/hyyan/woo-poly-integration/issues