I came to the conclusion acorn has troubles with multiple Sage themes in the wp themes folder. This is the main reason I didn’t got it to work. It saw two sage themes and asked me about 8 times which theme I wanted to install the component in. Selecting each time the right theme still did not help. It installed one of two files in the one theme and one file in the other theme. Another time it just kept installing it in the wrong theme. This is why it did not show up in my git status.