To start, the judiciary isn't part of the Spanish government, it's an independent branch like Congress. Like in most or all western countries. These actions have been taken by the order of Catalan judges.

If someone thinks the laws the judges are interpreting are unconstitutional, or against European treaties, they can denounce those laws against the Spanish Constitutional Court, or the appropriate European court.

If they think the interpretation is what's flawed, they can appeal and / or denounce the judges to the Spanish Supreme Court. If the argument would become that the judiciary is corrupt and owned by the Government, from the Barcelona courts all the way up to the Supreme Court; it should be remembered that the Spanish Supreme Court sentenced a Ministro del Interior (like Secretary of State, the de-facto most powerful position after the President) to 10 years in prison.