Thanks for the quick reply. I knew and use the handy guide but it does only work when you export the csv with the MacOS client. CSV exported by windows client are not working. FunFact: content look the same. Using the MacOS export works.
BUT:
The exported msecure csv has some weird content format. Every entry has the corresponding field name e.g. "username|01|John.Doe" included. This content is not usable because field name contains after the import the former msecure fieldnames. The imported content must be manually corrected.
Summarize: It looks like that the MSECURE import function is an ongoing construction site, because the topics pops up regulary. My issues occur with the actual V5 version.
The only solution at this point of time is to manualy clean and re-format the msecure csv to the default enpass csv import format as described.