in which language should I write my first draft a paper?
Personal opinion from a non-native english speaker:

You should write it as much as possible in english. Start working with bullet points of your ideas and then transfer them to full sentences after you are done. Since most academic papers are in english, it has already been mentioned on this platform a ton of times, that you should get used to the language, i.e. the vocabularies and the way people reason, in your field.