MariaDB ran mysql_secure_installation, but seeing remote login attemps in logs
Yes, the server would still be accepting remote connections. And yes, it probably did what it was supposed to do. mysql_secure_installation doesn't set bind-address=127.0.0.1 neither in MariaDB nor in MySQL. It does however allow you to remove root accounts that are accessible from outside of localhost, as you have already done.

If you don't have any database users with host != localhost, then remote login shouldn't be possible. You can of course also block the MariaDB server port in your firewall.