The ي in محامي is called ياء أصلية (original Yá'). It is part of the noun and has nothing to do with the suffix pronoun ـي (my).
It is one of the special cases in Arabic, that is when you added "my" to a word that ends with Yá' as well. In this case you would have to double the last letter of the noun (i.e. put Shaddah on it) with fatHa and the word becomes محاميَّ (MuHámiyya) - my lawyer.
On the other hand, This last Yá' in the noun should be omitted in specific cases. The above sentence in Arabic is wrong by the way because the Ya' should be omitted from محامي and must be replaced with Tanwin bil Kasr (-in) making the word: MuHámin محامٍ - because the word here is indefinite.
Another example when such words would have their Ya' omitted is in case of Genitive (adding nouns together), example: محامِ الدفاع (MuHámi-ddifá3: The defender, defending lawyer) -I'm typing phonetically here and not exactly how it is written in Arabic- In this instance though we didn't use Tanwin but simple Kasrah and the Yá was omitted.
Well, his translation is partially correct. However, Google or any translation machine i've encountered so far, are kind of short when it comes to translating proper Arabic. That's why I use them mostly for word-to-word and then I compose sentences from and into Arabic/English. Mostly now I use www.almaany.com which is a word-to-word dictionary only but it has some good jargon of scientific words and proper text examples sometimes (beside offering other languages other than English<->Arabic).
"a lawyer IS in Germany" would rather be translated as: هناك محامي في ألمانيا - By adding Hunák (there is) I'm turning the sentence into a complete "nominal" sentence telling about the fact of existence of a lawyer in Germany. The above sentence given by Duolingo is more like a predicative sentence (i.e. as if it was an answer to a question).