As a native German speaker I can confirm that they definitely are used. However, sometimes one must be careful. We like to use these words in a more specific context. Just two examples here:
We Germanized the verb "to chat" to "chatten". However, we only use it in the context of an electronic messenger conversation. When doing it in person, we'd rather use "plaudern" or "unterhalten"
Second example: "bug". We only use it in the context of programming errors in computer systems, not in the biological context, there the word would be "Ungeziefer" oder "Käfer"
Dies geht mir auf den Keks! Seriously, this has always bugged me about the German language. I hope (perhaps in vain) that one day the Germans will take pride in their language and go back to their German language roots. In the mean time, I have gone out of my way to invest a lot of time to learn German words where germanized English has been invented. And I use these words in my communication with Germans. Especially when they use a Denglish word with me. For example, "Hier musst du dich registrieren", and I respond, "Also, heir muss ich mich anmelden, richtig?".
For example, "Hier musst du dich registrieren", and I respond, "Also, heir muss ich mich anmelden, richtig?".
Would it be too mean-spirited of me to tell you that "registrieren" is a "real" German word, derived from Latin words like "registrare" or "registrum"? ;) There are a lot of loan words in current German, and some of them are really stupid, but in my opinion it's not worse than with just about every living language at about any time in history. Languages change, some changes will stick, others won't. The only languages that don't interact with other languages are dead ones. That's not to say that every loan word, every "borrowed" phrase is advantageous and useful. But sometimes it seems to me that cries like "They're mistreating their language by using foreign words!" are grounded more in the human reluctance to change in general ("It's different than it was before, we can't have that!") than in "real love" for a language ;)
And to make matters worse for your argument, "registrieren" and "anmelden" aren't the same thing. For example in an web application, "registrieren" means to create an user account, while "anmelden" means to log in with an existing account.
I'm happy enough for German to say 'Sinn machen' instead of 'Sinn ergeben'. The thing that gets on my nerves is the intersection of Denglish and business jargon. The words most enthusiastically adopted are those which have a cachet of modernity etc. in a business and advertising context. It's not English per se which is a bad influence, it's corporate culture, which just happens to be English-based.
No, it would not be too mean-spirited to say "registrieren" is a real German word in the same sense that "Kindergarten" is a real English word used to describe the first year of an American child's schooling. But in both cases, they are not native to their language. I am very aware of the etymology of registrieren, which goes to support the point I am trying to make. Plenty of synonyms in German already existed; and registrieren's rise in usage is tied in large part to the internet era in which we live. I am willing to bet using registrieren has become more popular in recent years due to the influence of English on the German language in business and online than its Latin etymology.
Registrieren appears to be trending downward since the 1980s https://books.google.com/ngrams/graph?content=registrieren&year_start=1800&year_end=2000&corpus=20&smoothing=3&share=&direct_url=t1%3B%2Cregistrieren%3B%2Cc0