  The dipolar-octupolar (DO) pyrochlores, R$_2$M$_2$O$_7$ (R = Ce, Sm, Nd), are
key players in the search for realizable novel quantum spin liquid (QSL) states
as a large parameter space within the DO pyrochlore phase diagram is theorized
to host QSL states of both dipolar and octupolar nature. New single crystals
and powders of Ce$_2$Sn$_2$O$_7$, synthesized by hydrothermal techniques,
present an opportunity for a new characterization of the exchange parameters in
Ce$_2$Sn$_2$O$_7$ using the near-neighbor $XYZ$ model Hamiltonian associated
with DO pyrochlores. Utilizing quantum numerical linked cluster expansion fits
to heat capacity and magnetic susceptibility measurements, and classical Monte
Carlo calculations to the diffuse neutron diffraction of the new hydrothermally
grown Ce$_2$Sn$_2$O$_7$ samples, we place Ce$_2$Sn$_2$O$_7$'s ground state
within the ordered dipolar all-in-all-out (AIAO) N\'{e}el phase, with quantum
Monte Carlo calculations showing a transition to long-range order at
temperatures below those accessed experimentally. Indeed, our new neutron
diffraction measurements on the hydrothermally grown Ce$_2$Sn$_2$O$_7$ powders
show a broad signal at low scattering wave vectors, reminiscent of a
\textit{dipolar} spin ice, in striking contrast from previous powder neutron
diffraction on samples grown from solid-state synthesis, which found diffuse
scattering at high scattering wave vectors associated with magnetic {\it
octupoles} and suggested an octupolar quantum spin ice state. We conclude that
new hydrothermally grown Ce$_2$Sn$_2$O$_7$ samples host a finite-temperature
proximate dipolar spin ice phase, above the expected transition to AIAO
N\'{e}el order.
