No, you may as well throw away the journal at this point, the data volume will be consistent as of the last checkpoint.
However multiple shards having the snapshots at different times will have irreconcilable inconsistencies. Without the recommended deployment of replicaSets for config and shards there are no secondaries that could be fsyncLocked so this must be done on the primaries.
Additionally the balancer must be stopped before the backup too:
https://www.mongodb.com/docs/manual/administration/backup-sharded-clusters/