Running Plone 5.1.4 with a custom content-types. The site was created from scratch with languages de+en.
The original content in EN shows up properly. When I click on "Create German" when I do not see the original content and its various fields. What could be the problem?
Unfortunately I can not recreate the problem because p.a.m before even more strange.
My content is in 'en':
(Pdb) self.context.language
'en'
(Pdb) self.context.absolute_url(1)
'scale/en/services'
I click on "Create German" and the @@create_translation redirects me to
/scale/en/++addtranslation++25a6bd2ee08e497494292e50a6b6891c
So why does the translation manager wants to create new content within the en language tree rather than the de tree?
The redirection however does not lead to the edit form but just reloads the default view of the existing english content.
Create an issue for that:
This is indeed the case...known bug?
Not sure if it's a "known" bug, I found out when first playing with it and documented it for our internal users 
We're using an older version, might not apply to you:
/usr/local/Plone5_ZEO/buildout-cache/eggs/plone.app.multilingual-5.0.3-py2.7.egg
Hitting the translate to English link on a German document gives me something like:
/plone/de/produkte/scholbeck-laerchengrau-vergrauungs-oel/@@create_translation?language=en
which then redirects to
/plone/en/products/++addtranslation++9035d19673ed4221addaf2e1312134a5
The bug is also in p.a.m. 5.2.3
Have you run the upgrade steps from p.a.m? a few weeks ago, i have a problem also with wrong redirects. i did not debug this, i run the upgrade steps in the zmi, and all was working like expected
This is a fresh installation