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Sorry your wife was given a 10 years route because she did not meet all the criteria but was granted the visa because of human rights reasons and not because of where she applied from. If by her next extension she meets all the criteria she will be granted on a 5 year route.
You cant reduce it to 5 years.
Like I explained to you, applicants are only given a 10 years route if they do not meet all the requirements. When she applies for an extension and she meets all the requirements she will be placed on a 5 year route. If not she will remain on a 10 year route
unfortunately already spent years are not included.