Will "bridge" storage engines work with MariaDB Galera Cluster?
Galera replicates DDL statements so other storage engines that act as a proxy to InnoDB tables or external systems should work normally.  The tables aren't really replicated but they would be created on each node when they are created on any node.


OQGRAPH - I saw you asking about it on the MariaDB site and as the consensus is there, theoretically it should work since the data is stored in InnoDB tables and would be replicated but it's not a common use case and you'll need to do some testing on your own.
Mroonga - same as OQGRAPH
CONNECT - This should be the same as OQGRAPH.
CassandraSE and SphinxSE - since the only information these engines use from MySQL is created with DDL statements, they should work fine.
BLACKHOLE - These are just normal tables that don't have any data to replicate so there shouldn't be any problems.
SEQUENCE - The SEQUENCE engine doesn't create any tables and is triggered by the names of tables in a query so these should work fine anywhere as long as the plugin is loaded on the server that is being queried.