Using neutrinos is far less efficient than using gamma radiation or neutrons or high energy electrons or ions for transmutations.

The photons/neutrons/electrons/ions have a high probability of interaction with the target, while the neutrinos have a very low probability of interaction.

All the elements that do not exist in nature due to low lifetime have been produced by transmutation, but this can be done only for very small quantities at huge prices.

In some sense this is how particle collisions works. You collide something and with certain probability you get something else at the other end under the physical constraints. Probably you want to use bigger particles and lower energy though to go from subatomic to atomic/molecular scale. The laser ignition fusion experiments would be closer to that. (Mind the costs though :))

https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

I imagine like a lot of the nuclear alchemy the cost is much higher than just getting the existing material you want.