Identifying impulse based on experimental data
Compute the position function from the accelerometer data using a scaled aggregator of some kind presumably, with initial conditions about resting position and velocity of the sound bowl. If you don't want to model the hammer's impact exactly, and want to think of it as an impulse, then the position function is the impulse response. Otherwise, go to 2.
Model the impact of a hammer as a non-ideal impulse function in time. Deconvolve the position function and the hammer model to get the impulse response. You could try to use the 3d fft on both these functions and find their ratio, and the compute its inverse 3d fft.