  Two-dimensional iron-chalcogenide intercalates display a remarkable
correlation of the interlayer spacing with the enhancement of the
superconducting critical temperature ($T_c$). In this work, synchrotron x-ray
absorption ($XAS$, at Fe and Se K edges) and emission ($XES$) spectroscopies,
allow to discuss how the important rise of $T_c$ (44 K) in the molecule
intercalated $\rm Li_x(C_5H_5N)_yFe_{2-z}Se_2$ relates to the electronic and
local structure changes felt by the inorganic host upon doping ($x$). $XES$
shows that widely-separated layers of edge-sharing $\rm FeSe_4$ tetrahedra,
carry low-spin moieties with a local Fe magnetic moment slightly reduced
compared to the parent $\beta$-$\rm Fe_{2-z}Se_2$. Pre-edge $XAS$ advises on
the progressively reduced mixing of metal $3d-4p$ states upon lithiation.
Doping-mediated local lattice modifications, probed by conventional
$T_c$-optimization measures (cf. anion height and $FeSe_4$ tetrahedra
regularity), become less relevant when layers are spaced far away. On the basis
of extended x-ray absorption fine structure, such distortions are compensated
by a softer Fe-network that relates to Fe-site vacancies, alleviating
electron-lattice correlations and superconductivity. Density functional theory
($DFT$) guided modification of isolated $\rm Fe_{2-z}Se_2$ ($z$, vacant sites)
planes, resembling the host layers, identify that Fe-site deficiency occurs at
low energy cost, giving rise to stretched Fe-sheets, in accord with
experiments. The robust high-$T_c$ in $\rm Li_x(C_5H_5N)_yFe_{2-z}Se_2$, arises
from the interplay of electron donating spacers and the iron-selenide layers
tolerance to defect chemistry, a tool to favorably tune its Fermi surface
properties.
