Trying to translate an object fails with the following error:
Uncaught InvalidCharacterError: Failed to execute 'createElement' on 'Document': The tag name provided ('structuredData#.content.0.BlogBundleWysiwyg.headline') is not a valid name.

This seems to stem from the # character. Replacing structuredData# with structuredData--- and classificationStore# with classificationStore--- in ObjectController.php and quickTranslateObjBtn.js solves the issue.
I'm currently using v3.0.10, but I believe the bug exists in v4 as well. Is it okay for me to open one PR for the master-3.x branch and another one for the current master?