ready2order, please forgive rushed reply here. Though Google has managed to improve its understanding of language delivery a lot over the years, it's still not able to deal with mixed languages on a page.
John Mueller has been on record in suggesting that site owners avoid mixing languages on a page.
We've had several discussions in this forum about the confusion that mixed languages can cause, and I'll link to them below.
In your case, you have a brand name composed of English words, which, as I noted in an earlier post, would complicate the issue significantly. IMO, an English language phrase as your (most likely) principle inbound anchor text might send such strong English language signals that Google would consider them more dependable than hreflang. Additionally, Google might need further signals to perceive these words as a brand.
My guess, an educated guess but still a guess, is that inbound linking sources and the language context of those links would have a lot to do with it... particularly if your brand name is seen simply as English language words and not as a brand entity.
You probably need more natural links with your brand name coming from German language pages that are hosted in German language countries... and these links need to go to the default page you wish to appear in German. You probably also need more natural occurrences of your brand name on authoritative pages within the context of all pages that Google relates to your site... eg, reviews, shopping directories, articles with citations about your site, etc.
You can find more detailed comments and discussion, from me and others, on these threads having to do with mixed languages.
Translate problem in Google SERP - not always ranking right language July 2010 https://www.webmasterworld.com/google/4169769.htm [webmasterworld.com]
This thread ^^^^ is prior to hreflang, which I believe wasn't introduced until 2011... but is one of our best discussions on mixed language issues... and many of the factors discussed still apply.
Apparently, hreflang hasn't resolved the issues of English language product names and synonyms, and they are discussed in this recent thread, I believe still open...
Google search console claims duplicated meta description, but not duplicated Dec 19, 2016 https://www.webmasterworld.com/google/4829516.htm [webmasterworld.com]
The problem exhibited is not exactly what you're experiencing, but I do bring up the issue of English words in product names on multi-language sites.
I believe that the solution the OP suggests in that thread is not applicable to your issue. It strikes me, though, that schema or rich data identifying your brand name as a branded entity might help Google sort out the language issue. You might find something helpful in "GoodRelations", an open-source approach to rich data for ecommerce. While I've not explored rich data to identify a branded entity, I have seen analogous situations that suggest it might be promising...
GoodRelations - The Web Vocabulary for eCommerce [
heppnetz.de...]
Please report back if you find something helpful....
PS: Edited for clarity.
