  Antiferromagnetic manganese-based nitride antiperovskites, such as Mn$_3$NiN,
hold a triangular frustrated magnetic ordering over their kagome lattice formed
by the Mn atoms along the (111)-plane. As such, frustration imposes a
non-trivial interplay between the symmetric and asymmetric magnetic
interactions, which can only reach equilibrium in a noncollinear magnetic
configuration. Consequently, the associated electronic interactions and their
possible tuning by external constraints, such as applied epitaxial strain, play
a crucial role in defining the microscopic and macroscopic properties of such
topological condensed matter systems. Thus, in the present work, we explored
and explained the effect of the epitaxial strain imposed within the
(111)-plane, in which the magnetic and crystallographic symmetry operations are
kept fixed, and only the magnitude of the ionic and electronic interactions are
tuned. We found a linear shifting in the energy of the band structure and a
linear increase/decrease of the available states near the Fermi level with the
applied strain. Concretely, the compression strain reduces the Mn-Mn distances
in the (111) kagome plane but linearly increases the separation between the
stacked kagome lattices and the available states near the Fermi level. Despite
the linear controlling of the available states across the Fermi energy, the
anomalous Hall conductivity shows a non-linear behavior where the
$\sigma_{111}$ conductivity nearly vanishes for tensile strain. On the other
hand, $\sigma_{111}$ fetches a maximum increase of 26\% about the unstrained
structure for a compression value close to $-$1.5\%.This behavior found an
explanation in the non-divergent Berry curvature within the kagome plane, which
is increased for constraining but significantly reduced for expansion strain
values...
