How will the Spanish court enforce their decision abroad? I know there are agreements between te countries, but what happens practically after a decision? Who gets activated in the US to enforce the decision?
You can take the judgement to a US court and it will be a simplied process. As long as it is a "normal" country like spain it shouldnt be a problem (if the court was say an Iranian court it might be more difficult).
Good answer and better question: Do civil law can enforce itself without bilateral agreements initiaing a claim to a foreign court? I don't think so. Even criminal couts can't without agreement.
Without agreements you go ahead and win your local case and then hope that the contract is enforceable in their country.
Thing is torts are very similar all over the place. Like if you are a former british colony your laws are usually roughly compatible. Most countries dont have a "contract was signed overseas fuckem" law. But some do.