IMHO NethServer 7 is still not ready for containers.
Current docker implementation is not mature enough to support all usage scenarios.
We can’t overcome this limitation without changing the current MariaDB configuration.
But such can affect other applications.
Honestly, I’m more than happy to leave with current limitation and avoid possible regressions 
Such indexes are not required for all installations. It really depends on the instance usage.
The admin is free to execute the suggested operations.
How could we improve it?
We are already using a not-recommended MariaDB version It seems that MariaDB 10.2 is the recommended one, but should work even with older releases.
If new releases of NC will not be compatible at all, we will try to switch to a new DB version using SCL.
Just like we did for Mattermost. 