Description

In WordPress core, there is a well established pattern where all the 'Add New' strings use title case, for example:

__( 'Add New Post' )
__( 'Add New Page' )
__( 'Add New Template' )

In the editor the situation is mixed. Sometimes it's title case, somtimes it's not. For example, even on the same line of code, this string uses inconsistent casing:

( slug === 'post_tag' ? __( 'Add new tag' ) : __( 'Add new Term' ) );

I'd think all these strings should be consistent with what Core does since ages and always use title case. Worth running a search through the entire code base and update all the inconsistent occurrences, where necessary.

See also on Core Trac:
https://core.trac.wordpress.org/ticket/47125
https://core.trac.wordpress.org/ticket/58577#comment:11

I'm not sure there is a good reason why tag should be lowercase while Term is title case. Also, the word new should always be title case.

Step-by-step reproduction instructions

• Run a case insensitive search in the codebase for all the strings that start with Add new.
• Observe the casing inconsistencies in your search results.

Screenshots, screen recording, code snippet

No response

Environment info

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Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes