I can't change the block name in Moodle 3.6.3 on "Site home" page. It's the Configurable Reports block. I changed the name in blocks settings and saved changes but default name "Configurable Reports" still appears in the block. I don't know if this is problem with configurable reports plugin or with Moodle core. Here are the screenshots...
Think you might need to explore Language edits to get what you desire.
"Configurable Reports" is the 'title' of the addon plugin - your second screen shot. Anything you create as a report (you name) would be under that.
But, have experienced that upgrades to Moodle might wipe out that language edit.
'spirit of sharing', Ken