Why better British machinery was not a simple answer for the Normandies

Would France have been better off buying British engines for the Normandie-class battleships?

Technically perhaps, but imported machinery would cost money abroad and fail to support France's own industrial base.

British engines could have given the Normandie class a better machinery option. That technical gain came with two institutional costs: France would spend money abroad and lose an opportunity to support its own industry. Naval procurement here serves budgets and industrial policy alongside ship performance.