Hierarchical term selector: don't use variables in translatable strings

[afercia]

In core, it's a long established, good, practice to avoid post types, taxonomies, etc. variable names for placeholders in translatable strings. It doesn't work due to structural differences in languages: feminine, masculine, various form of plurals, etc.

gutenberg/packages/editor/src/components/post-taxonomies/hierarchical-term-selector.js

Lines 373 to 388 in 910b655

	const filterLabel = sprintf(
	_x( 'Search %s', 'term' ),
	get(
	this.props.taxonomy,
	[ 'name' ],
	slug === 'category' ? __( 'Categories' ) : __( 'Terms' )
	)
	);
	const groupLabel = sprintf(
	_x( 'Available %s', 'term' ),
	get(
	this.props.taxonomy,
	[ 'name' ],
	slug === 'category' ? __( 'Categories' ) : __( 'Terms' )
	)
	);

These strings should be either simplified or use full translatable strings added in core for the taxonomies.

There are also other minor consequences. For example, in Italian (and I guess in many other languages) we don't use title casing. However, the first string placeholder is placed with the taxonomy name so the final result is a title cased string. Unpleasant to see, as all the other strings don't use title casing:

The second string is translated as:

aria-label="Disponibile Categorie"

which is wrong, but I can't blame translators as _x( 'Available %s', 'term' ) is difficult to translate and not visible in the interface.

In these cases, I'd recommend to:

• either simplify the strings and remove placeholders
• or introduce new taxonomie label in core and use them in the editor