In fact, there are no "authorities", in the sense that anyone can become a Sagemath developer, and
anyone doing a GSoC on Sagemath would in effect be a Sagemath developer. See
E.g. as a first task, you might identify the relevant parts of Sagemath code written with old Cython features,
and propose better implementations. E.g. Cython has a better support of C++ now, and you might see
how this can be utilised to improve interfaces to libraries related to computations with polynomials.
Thank you!