Thanks for the suggestion. But after renaming the issue persists. Actually, I came across this error using another gen patch where the parameter Delay doesn't exist. It seems inherent in the Delay method. And sure, using the parameter Dalay isn't really a good idea.
Found it. My suspicion that there is a naming conflict was right. "Delay" is used by Apple in CoreServices.framework/Frameworks/CarbonCore.framework/Headers/OSUtils.h. Found this after performing "Product->Perform Action->Preprocess "gen_exported.cpp"". After renaming "Delay" to e.g. "GENDelay" at all locatons the project builds, but: the product shows only up as a folder and auval and any audio app I tried don't see it as plugin. Hm.