In magnetism, the antiferromagnetic interaction between ising spin on a regular triangle is the simplest example of geometrical frustration. Is it possible that this frustration relieved for Heisenberg spins??
No. Even for Heisenberg spins the lattice is still frustrated.
In order to remove the frustration you have to distort the lattice (i.e. introduce a difference in the coupling paramters) or introduce interactions with second or third neighbors (can't remember the details, sorry).