Can there be "too much" capacitance on a buck regulator output?
If you want to suppress the ripple more, you can add more output capacitance BUT don't place it directly in parallel with the 10uF output capacitor. Instead, make an LC filter so first through an inductor or a choke, after this you can add almost as much caps as you like. The extra inductor or choke will prevent the extra caps affecting the regulator's loop.

Like so:







simulate this circuit &ndash; Schematic created using CircuitLab