Hello

Could you tell me whether the sentences below are correct?
1. The lessons were adapted to my level of advancement. (I am talking about German lessons; I mean my level of advancement in German).
2. Mr Brown possesses great pedagogical skills and creates a perfect environment for learning German.
3. Mr Brown has used a wide variety of teaching materials. He has also prepared diverse exercises (connected with grammar, vocabulary, word formation, etc.) in order to address all the areas of the language.
4. The vocabulary presented during the classes was adapted to my needs.
5. Communication during the lessons was facilitated due to Mr Brown’s great command of the Spanish language.
6. Mr Brown is an enthusiastic teacher as well as a skilled listener and communicator.
I was also wondering whether the word 'great' sounds too informal in official documents?
Thank you for your help.
Kind regards.