Are you using EPEL package ? or Firebird project binaries ? There is a compilation issue in Epel package since 2.5.8, and nobody understand exactly what fbintl from 2.5.7 package is ok
cf https://bugzilla.redhat.com/show_bug.cgi?id=1636177 and http://tracker.firebirdsql.org/browse/CORE-5925 but you can use firebird 3 https://copr.fedorainfracloud.org/coprs/makowski/firebird/
