I'm a developer, i may answer these questions, from google / apple perspective, the one who is responsible for the content is the owner of the app or the owner of the developer account, who have the developer ID and therefore can upload the app to the appstore. If the app raised a red flag, the account owner admin is the one who answer the complain.
So usually i don't upload clients app to my developer account, i set them up with their own account so all apps i developed for them will be on their own account. Use their Credentials, emails and address, and their credit card to pay for the registration, never use your bank account. In google case, if one of your developer account was banned, usually they would ban multiple account linked to you, including youtube, admob etc. If you're banned, you are not allowed to make money in all google platform.
So my suggestion is keep your account clean, play with the rules, and not worry with clients, keep everything separated and you will be good.