Isn’t the Many-World interpretation improbable? The Many-Worlds interpretation is possible when the event at issue has a 50-50 probability.  It becomes suspect when the probability of an event is not 50-50.  The prime example is experiments with entangled particles with correlation results violating the Bell inequalities.  For example, at the maximum positive difference there is an approximately 71% correlation between entangled particles (showing lack of locality) in comparison to the classical outcome of 50% correlation. 
The Many-Worlds interpretation includes the assumption that the laws of physics (and the Schrödinger equation) are the same in each world.  That means that in each of these worlds the 71% correlation applies (assuming the experimental parameters are set correctly).  
For the MWI to be correct, though, the events happening here must have opposite outcomes in other worlds. Our world having a 71% correlation at the optimal settings means that there must be a corresponding total 71% non-correlation in other worlds.  The problem is that each of those other worlds must have its own 71% correlation, leading again to a total 71% non-correlation in other worlds.  Presumably decoherence has been happening since roughly the time the Universe began.  Doesn’t this mean that it’s extremely unlikely the MWI is correct, even though this does not prove that the MWI is wrong?
 A: The word "interpretation" means that the mathematics of the model give the same results as Copenhagen interpretation. I have discussed this here and  recently here . It is not possible to think of a way to falsify an interpretation, by construction of the word "interpretation"
This shows some of the mathematical paths that enter the infinite sum that gives the probability distribution  of a particle to go from A to B. It is a sum of all that gives the prediction, not the individual paths:


These are just three of the paths that contribute to the quantum amplitude for a particle moving from point A at some time t0 to point B at some other time t1. 

Mathematically you could call each path a reality, but there is no way to check it.
It is only when extra conditions are used, and it is not just an interpretation any longer, that measurable differences can be found. But then it is no longer a physics model but a metaphysics one, because at present there is no experimental evidence of the need for many worlds models.  
Your assumptions in the last paragraph assumes that measurements can be made that show the difference, which means you are not looking at an interpretation but at an alternate model. If it is an interpretation it is correct by definition. If extra hypothesis are used it is a different model of reality than the one we have recorded up to now.
