The reporter can be used to test crash-safety of replication.
It is a periodic reporter, every 30 seconds it kills the slave server using SIGKILL, and immediately restarts it on the old data directory, with the same parameters as before. On server restart, the reporter checks that the server itself and the replication started all right.
The reporter itself does not check consistency of the data, but it can be used together with ReplicationConsistency reporter.
It is supposed to be used with runall-new.pl, so that the server is started without MTR involvement.
Some more information at https://kb.askmonty.org/en/rqg-extensions-for-mariadb-features/