I'm assuming the 10% risk number that would have been closer to 18-20% if you'd rejected the drugs.
And luckily you've done well and dodged those 10% 'odds' of recurrence. So it sounds as if the drugs have worked and it would make sense that the risk, based on genetics, remains about the same as both tests test genes. Though there's variance in the algorithms and the tests are done to answer a different question.
Had genetic mutations occurred on the alleles targeted by the tests, your risk would likely have worsened. So it's a question of continuing the drugs (which makes sense) or again looking at a higher double-digit risk. If you tolerate the drugs OK, and monitor for osteoporosis, taking the drugs seems wise. How are you looking at it?

The Breast Cancer Index tells you yes or no, whether extended endocrine therapy is of any benefit. This is unrelated to risk. In other words, you can be of high risk but not benefit and you can be of low risk and still benefit. @huey it sounds like you were classified as high risk by the BCI but still benefit from more years on the meds.

ps @callalloo with a score of 10 on the Oncotype, I would assume a risk of, say, 6% or something like that.