  We propose a Bayesian inference estimation of in-medium modification of the
cluster self-energies from light nuclei multiplicities measured in selected
samples of central $^{136,124}$Xe$+^{124,112}$Sn collisions with the INDRA
apparatus. The data are interpreted with a relativistic quasi-particle cluster
approach in the mean-field approximation without any prior assumption on the
thermal parameters of the model. An excellent reproduction is obtained for H
and He isotope multiplicities, and compatible posterior distributions are found
for the unknown thermal parameters.
  We conclude that the cluster-$\sigma$-meson coupling is temperature
dependent, becoming weaker when the temperature increases, in agreement with
microscopic quantum statistical calculations. This implies a faster decrease of
the light cluster abundances with temperature than previously estimated.
