Just as Du Pont had bought gunpowder-making equipment from France, Americans wanted to buy Louisiana, and bankers from every country had flocked in, bankers could not be made to invest in Belgium through coercion. There had to be a detailed business plan. After all, post-Revolution France was no longer a monarchy.
Overall, Bonaparte's plan was to turn Belgium into a light-industrial base, including but not limited to sugar refining and distilling. Equipment would be imported from France, sugar beets grown locally, and, while ensuring France's food security, crops such as wheat exported to Belgian distilleries to generate income for farmers. Farmers would change their methods of production and increase yields per acre.
That was the rough blueprint. More details still had to be added, such as means of transport. Austria had also built a "railway" running between its spa resorts and Vienna. It was not merely for the convenience of nobles, but because nobles could afford to pay.
Through the Treaty of Campo Formio, Napoleon had made Austria compensate Belgium for its national debt. Without issuing paper currency, they could only increase revenue and cut expenditure to restore national strength. As a result, the size of their army would be restricted.
Likewise, banks from various countries pressured the Consulate. Repaying the old loans used to buy grain for disaster relief was another restraint. A great power with poor credit severely dampened investors' enthusiasm. That debt would not vanish with Louis XVI's death. Unless all the people of France repaid it, France's credit rating would not rise, leaving France in a very passive position in the international market.
The Treaty of Paris stipulated that America would repay the debts Britain had lent it before the war, not the wartime loans that lunatic had just mentioned. The difference between before and after