Counterfactuals vs. Material Conditions: What Makes an Economic Model Scientifically Useful?

I have read this recent report from the Cuba Transformación project. This is an initiative advanced by five Cuban economists to generate fresh ideas to boost our economy. I’m not going to discuss the essence of the specific economic proposals, which seem relevant to me. As a rule, the first thing I look for in analyses by economists like these five is how they value the impact of the external factor in the Cuban crisis. I argue that they tend to relativize the accumulated and integral impact of the U.S. sanctions regime against Cuba, the most comprehensive one that country applies worldwide —this last is not an opinion, it is a fact.
The Cuba Transformación report seems very representative of that tendency. It presents a basic flaw by assuming a scenario in which there has been a substantial flexibilization of U.S. economic sanctions. For the Cuban case, it is a very limited theoretical exercise. What the country demands are scientific proposals to grow under the effects of that siege, not laboratory science. If the political problem is not resolved, what happens to this work? If it does not manage the context as it actually is, but instead depends on a factor it does not control, what practical and immediate relevance does it have beyond theory?
Then, according to the report, the "fundamental cause" of the structural crisis of the Cuban economy lies in the "persistence of a model of centralized planning that has proven incapable of generating sustained growth". My question is: on what scientific basis is this stated? In other words, where is the scientific study that estimated the responsibility of the external factor versus the internal one? This is, of course, a complex analysis to produce, but if one claims that the internal variable is the main one, I suppose there must be hard statistics and mathematics to sustain that claim.
I also want to see the study that has estimated where Cuba would be —even taking into account ALL the well-known internal management problems— without sanctions. It is not about thematizing the external variable, but about seeking and advancing an analysis that understands the whole picture, drilling deeply into each part or element that forms the picture. This is a persistent debt in the debate on Cuba.
