Surface of the intersection of $n$ balls
Surface and volumes can be calculated analytically for any n value. For intersections of n=5 spheres and more, they can be calculated from the 4 by 4 intersections: see theorems 4.5 and 4.6 in my book chapter:
Spheres Unions and Intersections and some of their Applications in Molecular Modeling, In: Distance Geometry: Theory, Methods, and Applications, chap. 4, pp. 61--83. Mucherino, A.; Lavor, C.; Liberti, L.; Maculan, N. (Eds.), Springer, 2013. ISBN 978-1-4614-5127-3, DOI 10.1007/978-1-4614-5128-0_4
A free preprint is available at: https://hal.archives-ouvertes.fr/hal-01955983