Hey there,
I guess I've found an issue regarding the translation of block.json content. I'm not quite sure where the exact problem is: WP-CLI or the Gutenberg project?

Summary:
After generating PO- and JSON-Files with the according CLI-commands Gutenberg does not translate strings from block.json.

Steps to reproduce:

1. Install a Test block
   cd /wp-content/plugins
npx @wordpress/create-block my-test-block

2. Edit /src/index.js to use block-meta:

import metadata from './block.json';
registerBlockType(metadata, {
	edit: Edit,
	save,
});

3. Fix editorScript path in block.json (otherwise MD5-hashes are not correct)

{
	"editorScript": "file:index.js",
	...
}

4. Create POT
   cd /my-test-block
wp i18n make-pot . languages/my-test-block.pot --skip-php --exclude=build,node_modules

5. Create PO-File and translate (at least the strings from the block.json)

6. Create JSON-File:
   cd languages
wp i18n make-json my-test-block-de_DE.po ./ --no-purge '--use-map={ "src/index.js": "build/index.js", "src/save.js": "build/index.js", "src/edit.js": "build/index.js", "src/block.json": "build/index.js" }'

7. Run build
   cd wp-content/plugins/my-test-block
npm run build

8. Fix path in my-test.block.php

add_filter(
	'load_script_translation_file',
	function ( string $file, string $handle, string $domain ) {
		if ( 'my-test-block' !== $domain ) {
			return (string) $file;
		}

		return plugin_dir_path( __FILE__ ) . 'languages/' . basename( $file );
	},
	10,
	3
);

8. Activate plugin and add the block into a post. Set language accordingly.
   The title is not translated.

Environment
wp cli info

OS:     Darwin 21.3.0 Darwin Kernel Version 21.3.0: Wed Jan  5 21:37:58 PST 2022; root:xnu-8019.80.24~20/RELEASE_ARM64_T8101 arm64
Shell:  /bin/zsh
PHP binary:     /opt/homebrew/Cellar/php@7.4/7.4.28.reinstall/bin/php
PHP version:    7.4.28
php.ini used:   /opt/homebrew/etc/php/7.4/php.ini
MySQL binary:   
MySQL version:  
SQL modes:      
WP-CLI root dir:        phar://wp-cli.phar/vendor/wp-cli/wp-cli
WP-CLI vendor dir:      phar://wp-cli.phar/vendor
WP_CLI phar path:       /Users/fs/Local Sites/meinwp/app/public/wp-content/plugins/my-test-block/languages
WP-CLI packages dir:    
WP-CLI global config:   /Users/fs/.wp-cli/config.yml
WP-CLI project config:  
WP-CLI version: 2.6.0

Expected Result
I would expect that the block title and the description gets translated.

Actual Results
Title and description gets not translated.

Any help is much appreciated.