Currently, this project expects to be built with the Intel MKL packages provided directly by Intel. However, that APT repository has been deprecated, and it is becoming increasingly difficult to use it on modern systems.
MKL packages are now widely available from the repositories of APT distros, but they install the libraries and headers at standard paths in /usr/, rather than the obscure locations in /opt/intel that were used previously. Would you consider cherry-picking this commit from upstream, which allows CMake to find the libraries from standard paths?
marian-nmt@8ecc8b6
Bergamot-translator works fine with this change, on my Debian Unstable machine (as tested by building and running translateLocally).