Modify the InnerBlocks ‘Add block’ block appender label

I’m using the button appender as specified in the docs.

// Utilise a predefined component
<InnerBlocks
    renderAppender={ InnerBlocks.ButtonBlockAppender }
/>

By default the title of the appender (when hovered over) is "Add block". I’d like to change this to a custom title without having to define a completely new custom appender. I can’t find any way to do this after looking through the docs and block editor source code.

I see that the core Buttons and Columns blocks do this and modify the appender to "Add Button" and "Add Column" respectively. But so far I’ve been unable to locate where in the code the appender titles are modified.

Perhaps this is being done by updating the translation strings as someone suggested on Twitter.