这个 of people who can read colors with their finger 作 several cases 的定语,原本应放在前面 cases 之后,但由于太长,导致谓语（have been reported）与主语之间相隔太远,因此后置了.
主语：several cases
定语：of people who can read colors with their finger
谓语：have been reported
状语：in Russia recently
全句：最近俄罗斯报道了几宗人用手指就能辨别颜色的案例.