  The Be isotopic measurements preliminarily reported by the AMS-02
Collaboration have reached an unprecedented energy of 12 GeV/$n$. As secondary
cosmic rays (CRs), the Be isotopes include both stable and unstable species,
which are crucial for constraining the propagation parameters of Galactic CRs.
However, uncertainties in their production cross sections can skew the
interpretation of the CR data, especially when cross-section measurements are
of significantly lower quality than CR measurements. In this work, we consider
the uncertainties of the cross sections to interpret the Be isotopic data by
adopting a cross-section parametrization that fully utilizes the available
experimental data. Owing to the high-quality measurements of the $^7$Be
production cross section, we innovatively employ $^7$Be instead of $^9$Be to
constrain propagation parameters. Notably, the diffusion halo thickness is
constrained to $5.67\pm0.76$~kpc, representing a moderate value compared to
previous analogous works. Combining the well-constrained CR propagation model
and the precise CR measurements of $^9$Be, we conversely constrain the major
production cross section of $^9$Be and find that it ought to be remarkably
lower than previously thought. Our analysis also questions the reliability of
certain cross sections measured by some experiments, potentially marking the
first time CR data has been used to identify dubious nucleon production cross
sections. The method presented in this work holds promise for analyzing
upcoming isotopic data from other nuclei.
