Working example without Fluidcontent?

[MediKathi]

Hello, i have been working for a pure Flux solution, to get this feature working (fluidcontent ist now marked as obsolete, so I want to migrate to FLUX see https://github.com/FluidTYPO3/flux/issues/1542 ).

I was able to get a Working result in the Frontend, but with any kind of <f:translate ...> in the backendpart of a Content Element, I got "Parameter $extensionName cannot be empty if a fully-qualified key is not specified." is there a way to get this working, or is there a Working example?

I have a Locallang.xlf in my extension with all the Labels of my content-elements.