Ultrasound cleaning of Indium should indeed be one of the easiest way cause transmutation. Some of energy of ultrasound create 13.6 ev photons from ionization of hydrogen. Some of hydrogen plasma generates phats of 13.6 ev photons. Some of these phats are at 54.4 ev. Indium’s 4th ionization potential is also 54.4 ev, so ultrasound can channel 54.4 ev energy via a weak interacting state in Indium into the nucleus of Indium as w-wave energy. W-wave energy that transfers into the nuclear region create a giant dipole which shields nuclear charge. Because of the number of nucleons in Indium is so large, Indium acts a trap for w-wave energy. As energy builds in the giant nuclear dipole, the shielding reaches a critical value where fusion can occur at low energy.
Because the cavitation bubble act locally, many Indium atoms are energized to the point of fusion at once. The dominate fusion should be Indium to Indium which is followed by fission. W-waves as products are rapidly exchanged from products atoms to reactant atoms, which result in a local burst of fusion which is followed by fission moving outward from the point of origin. Hora et al in ICCF-7 provide an equation for the expected distribution of atomic numbers of daughter products which should be applicable here.
The fusion to fission accounts for the large number of elements which are produced. It also account for some product elements being larger that Indium and some smaller than Indium.