  We calculate the scalar spectral index $n_s$ and the tensor-to-scalar ratio
$r$ in a class of recently proposed two-field no-scale inflationary models in
supergravity. We show that, in order to obtain correct predictions, it is
crucial to take into account the coupling between the curvature and the
isocurvature perturbations induced by the noncanonical form of the kinetic
terms. This coupling enhances the curvature perturbation and suppresses the
resulting tensor-to-scalar ratio to the per mille level even for values of the
slow-roll parameter $\epsilon \sim 0.01$. Beyond these particular models, we
emphasise that multifield models of inflation are a priori not predictive,
unless one supplies a prescription for the post-inflationary era, or an
adiabatic limit is reached before the end of inflation. We examine the
conditions that enabled us to actually derive predictions in the models under
study, by analysing the various contributions to the effective isocurvature
mass in general two-field inflationary models. In particular, we point out a
universal geometrical contribution that is important at the end of inflation,
and which can be directly extracted from the inflationary Lagrangian,
independently of a specific trajectory. Eventually, we point out that spectator
fields can lead to oscillatory features in the time-dependent power spectra at
the end of inflation. We demonstrate how these features can be model
semi-analytically as well as the theoretical uncertainties they can entail.
