So one thing to note is detangling European ethnic DNA is very tricky due to the many different migrations between the different populations. This is especially true in continental Europe such as Germany and surrounding areas. Basically you're going to have a hard time determining German from Irish from English from Scottish from French, etc. Ethnicity in DNA is more useful for identifying very different DNA like European from African from Native American and East Asian etc.

On top of that you inherit autosomal DNA randomly. So your DNA does not represent all of your ancestral branches equally.

Basically don't expect ethnicity estimates to help with genealogy (except as I mentioned for some of the more diverse populations like African or Native American). Cousin matches are *much* more useful, find at least 2 other people who share the same segment in your DNA (more is even better) and try and find where you all overlap, this can confirm your paper trail nicely or bring up additional alternatives.