Good evening, I think this is an issue with the package 389-dsgw, but basically following the same as the already mentioned issue #737214, a link helped, though I did use the x86_64 version.
ln -s /usr/lib/x86_64-linux-gnu/nss/libsoftokn3.so /usr/lib/x86_64-linux-gnu/ Afterwards the configuration did work successfully. Best regards Thore