  We show that the mesoscopic incommensurate $\mathbb{Z}_2$ vortex crystals
proposed for layered triangular anisotropic magnets can be most saliently
identified by two distinctive signatures in dynamical spin response
experiments: The presence of pseudo-Goldstone `phonon' modes at low frequencies
$\omega$, associated with the collective vibrations of the vortex cores, and a
characteristic multi-scattered intensity profile at higher $\omega$, arising
from a large number of Bragg reflections and magnon bandgaps. These are direct
fingerprints of the large vortex sizes and magnetic unit cells and the
solitonic spin profile around the vortex cores.
