Others have mentioned the Societas Europea, which I think is the correct way to do this--provide an option to use a pan-EU legal form. The other way--mandatorily replacing member states' legal forms with one or more pan-EU forms--would simply be too disruptive. You'd be forcing hundreds of thousands, if not millions, of companies to change their legal form. Even if you tried to make the conversion process automatic, there's no one-size-fits-all approach to converting every company that won't end up with some companies automatically adopting constitutions that don't make sense (for example).
Some particular aspects of company law are partially harmonised at EU level, for example insolvency law. But that's mostly about ensuring that cross-border insolvencies don't become hopelessly complicated and bogged down through parallel proceedings.
Some particular aspects of company law are partially harmonised at EU level, for example insolvency law. But that's mostly about ensuring that cross-border insolvencies don't become hopelessly complicated and bogged down through parallel proceedings.