GLOBAL scope does not work as expected for Document Translation Bundles

Step to reproduce

• In main wiki, create a page Sandbox.L10N.WebHome and add a TranslationDocumentClass object to it.
• Configure its TranslationDocumentClass object with scope "GLOBAL"
• Add translation key/label to the page content: core.tags.list.label=Topics
• Make sure the page content uses syntax plain/1.0
• Save page

Actual result

• On the main wiki, the "Tags" label in the document footer reads "Topics" as expected.
• However on a subwiki the label remains "Tags" while "Topics" would be expected as well, since the bundle scope is global.