Adsense is one of the best ad agency that I have ever seen. I am using adsense to earn revenue for more than 2 years. In my experience with adsense and other advertisement plans adsense is genine and best plan. If you have adsense account then you probably dont want to loose it due to your silly mistakes. The best idea is to follow the policies that has been published by adsense. But these policies might not give idea about the issue that this topic is giving.
As my experience after you get aproval of Adsense if you change your theme, it does not affect the adsense advertisement. you are free to change your theme.
But the thing you have to keep in mind is you must check the loading speed and mobile friendliness of theme before you deside to change the theme. The theme you are going to change shoulld be fast enough to load content and responsive.
