  Motivated by recent experimental findings on the low-energy spectrum of
Kekul\'e-patterned graphene, the optoelectronic signatures of graphene
superlattices with a spatial modulation that triples the size of the unit cell
and folds the valleys to the center of the Brillouin zone are studied. For
superlattices like those visualized in recent experiments, the optoelectronic
response reveals multiple species of carriers distinguished by their effective
masses or Fermi velocities. Their signatures are similar to those of systems
hosting multifold fermions in which different frequency intervals are dominated
by different types of quasiparticles. Remarkably, the response of these systems
exhibits a characteristic peak in the optical conductivity suggesting a kind of
moir\'e interference between the different species of carriers. We also show a
relation between these systems and moir\'e superlattices by obtaining a minimal
model for a graphene superlattice that exhibits flat bands like those found in
twisted graphene bilayers.
