  We investigate multi-field signatures of the nonminimally coupled
supersymmetric Higgs inflation-type cosmological scenario, focusing on the
two-field Higgs-lepton inflation model as a concrete example. This type of
inflationary model is realized in a theory beyond the Standard Model embedded
in supergravity with a noncanonical K\"{a}hler potential. We employ the
backward $\delta N$ formalism to compute cosmological observables, including
the scalar and tensor power spectra, the spectral indices, the tensor-to-scalar
ratio and the local-type nonlinearity parameter. The trajectory of the inflaton
is controlled by the initial conditions of the inflaton as well as by the
coefficients in the K\"{a}hler potential. We analyze the bispectrum of the
primordial fluctuations when the inflaton trajectory deviates from a straight
line, and obtain constraints on the noncanonical terms of the K\"{a}hler
potential using the Planck satellite data. Our analysis represents a concrete
particle phenomenology-based case study of inflation in which primordial
non-Gaussianities can reveal aspects of supergravity.
