I want to understand the famous scene of movie "Der Untergang" (or Downfall) without looking at subtitles. I found out the official English subtitles do not translate the sentences very accurately both in terms of words and in terms of grammar.
For example, "Und im Osten ist der Feind bis zur Linie Lichtenberg, Mahlsdorf und Karlshorst gelangt" is translated to "In the east, they reached Lichtenberg, Mahlsdorf and Karlshorst" in the English subtitle, while based on my searching it actually means "In the east, the enemy reached to the line formed by Lichtenberg, Mahlsdorf and Karlshorst" to be accurate.
However even though I am able to figure out the accurate meaning of some sentences like the above one using sites like context.reverso.net, sometimes I am just not able to do so as I have no prior knowledge of the German language. For instance the word "dich doch" sometimes means "calm down" and sometimes means "yourself" based on my searching and I am not sure which meaning is used exactly in the movie. Other times, I can find out what a single word means but cannot make sense of the grammar or how the words connect.
Is there an efficient way of learning, or website, or service that can let me understand specific sentences grammatically and systematically for the German language?