Creating folder in multilingual setup fails for folder-id "subjects"

[skillfully]

BUG/PROBLEM REPORT (OR OTHER COMMON ISSUE)

What I did:

• setup a vanilla Plone instance v5.1.6 without p.a.m installed
• create a folder with title/id "subjects"
  • the folder is created
  • the folder is accessible
  • you can edit the folder or create other content inside

OTHERWISE

• setup a vanilla Plone instance v5.1.6 with p.a.m installed and 2 languages configured; for example german & english
• create a folder with title/id "subjects" inside the language root folder
  • the folder is created, but the view is not accessible
  • in ZMI
  • you can see the folder inside the language root, but it is not accessible
  • in portal_catalog the folder is indexed

What I expect to happen:

It should be possible to create a folder with title/id "subjects" in a Plone instance with p.a.m installed

What actually happened:

The folder seem to be created, shown in ZMI and folder listing, but is not accessible.

What version of Plone/ Addons I am using:

• Plone 5.1.6 (5116)
• CMF 2.2.13
• Zope 2.13.29
• Python 2.7.17 (default, Nov 7 2019, 10:07:09) [GCC 7.4.0]
• PIL 5.2.0 (Pillow)
• plone.app.multilingual 5.2.3

[krissik]

I have seen this error today (Plone 5.2.7). A user created a folder named "subjects" but this folder was not accessible. This was the error message:

Forbidden: The object at https://xyz/en/fb10/xyz/subjects has an empty or missing docstring. Objects must have a docstring to be published.
  File "ZPublisher/BaseRequest.py", line 518, in traverse
    subobject = self.traverseName(object, entry_name)
  File "ZPublisher/BaseRequest.py", line 349, in traverseName
    ob2 = adapter.publishTraverse(self, name)
  File "opt/plone/buildout-cache/eggs/plone.dexterity-2.10.5-py3.7.egg/plone/dexterity/browser/traversal.py", line 52, in publishTraverse
    request, name
  File "ZPublisher/BaseRequest.py", line 148, in publishTraverse
    "published." % URL

NotFound: subjects
  File "ZPublisher/WSGIPublisher.py", line 162, in transaction_pubevents
    yield
  File "ZPublisher/WSGIPublisher.py", line 371, in publish_module
    response = _publish(request, new_mod_info)
  File "ZPublisher/WSGIPublisher.py", line 250, in publish
    obj = request.traverse(path, validated_hook=validate_user)
  File "ZPublisher/BaseRequest.py", line 540, in traverse
    return response.forbiddenError(entry_name)
  File "ZPublisher/HTTPResponse.py", line 1009, in notFoundError
    raise exc