I18n localization in Confluence Cloud

I’m developing a simple Concluence Cloud addon that does nothing but serve a few blueprints. I’d like to offer those blueprints in multiple languages. This was rather easy for the Server version, but I can’t make it work for Cloud.

I’ve created created i18n JSON files as described here, put them into the public folder, and included their paths in the addon descriptor. When running the addon, the logs show that the language files are indeed successfully fetched by Confluence; however, Confluence doesn’t seem to use them. The blueprint shows up with its fallback name, and using the blueprint results in i18n resolved string: hello.world.

What am I missing?

atlassian-connect.json

{
  ...

  "translations": {
	"paths": {
	  "en-US": "/i18n/en_US.json",
	  "de-DE": "/i18n/de_DE.json"
	}
  },
  "modules": {
	"blueprints": [
	  {
		"template": {
		  "url": "/blueprints/my-blueprint.xml"
		},
		"createResult": "edit",
		"key": "my-blueprint",
		"name": {
		  "value": "Fallback Name",
		  "i18n": "hello.world"
		},
		"icon": {
		  "width": 80,
		  "height": 80,
		  "url": "/images/blueprint-icon-80x80.png"
		}
	  }
	]
  }

 ...
}

de_DE.json

{
  "hello.world": "Hallo Welt"
}

my-blueprint.xml

<p>i18n resolved string: <at:i18n at:key="hello.world" /></p>