  Charge-exchange reactions are versatile probes for nuclear structure. In
particular, when populating isobaric analog states, these reactions are used to
study isovector nuclear densities and neutron skins. The quality of the
information extracted from charge-exchange data depends on the accuracy of the
reaction models and their inputs; this work addresses these two points. First,
we quantify the uncertainties due to effective nucleon-nucleus interactions by
propagating the parameter posterior distributions of the recent global optical
model KDUQ [1] to $(p,n)$ reaction observables populating the isobaric analogue
state, at beam energies in the range of $25-160$ MeV. Our analysis, focusing on
$^{48}$Ca, shows that the total parametric uncertainties on the cross sections
are around 60-100%. The source of this uncertainty is mainly the transition
operator as the uncertainties from the distorted waves alone are less than
about 15%. Second, we perform a comparison between two- and three-body models
that both describe the dynamics of the reaction within the DWBA. The
predictions from these two models are similar and generally agree with the
available data, suggesting that 1-step DWBA is sufficient to describe the
reaction process. Only at a beam energy of 25 MeV there are possibly signs that
a 1-step assumption is not fully correct. This work provides motivation for the
quantification of uncertainties associated with the transition operator in
three-body model. It also suggests that further constraint of the optical
potential parameters is needed for increased model precision.
