Hi! We are considering ShipStation for one of the future versions (among other possible features), but it’s too early to commit to any release dates just yet.
Our plans for CS-Cart 4.18.1 are already packed (we’re revamping the control panels of admins and sellers). The UI and UX improvements should continue even after 4.18.1, but by then we should have more resources for new integrations.
By the way, if you have any reasons why you’d prefer ShippyPro or GoShippo over it, please let me know. Also, feel free to say if there’s anything in particular you’d expect from a ShipStation integration, that could help me too.