Meanwhile we know, what the reason was for this strange behaviour:
We are using custom-installations of Arbortext Editor. For this installations we have customizations zipped in custom.zip. As we know in this custom.zip there should only be content of customizations. For example .acl - Skripts, java classes and so on. Therefore in our zip there are also only this customizations inside. But unfortunately Arbortext Editor need in doctypes the folder 'eventlog' to get the correct completeness check results like in your screenshots.
We dont know why this folder must be a part of the customizations, but this was the solution in this case.