Liberal is used as a descriptive term in the US while in this case it’s part of a party name. Party names don’t have to – for various historical reasons – reflect the current political positions of a party (think US party names). That’s especially the case in current European democracies with proportional representation. All the parties have very similar positions close to the center, it’s easy for any one party to end up to the “left” or “right” of other parties on any one issue.

(Liberal also doesn’t have the same meaning in Europe as in the US. Liberals in Europe are usually socially permissive as well as economically permissive – like Libertarians in the US. But that doesn’t have anything to do with the point you are making – Malmström’s position is not exactly socially permissive.)