No, not really. A judge would apply the rules as they exist. And then, depending on the case it would follow the local country’s appeal process and possibly end

No, not really. A judge would apply the rules as they exist. And then, depending on the case it would follow the local country’s appeal process and possibly end up at the CJEU. But even then it would not change the rules. Any change of rules needs to be drafted by the commission or proposed in parliament, and then accepted by the parliament. The EU does not really do common law. Not like in the US anyway.