Regarding APIs for Team shared folder and non shared folders

The [''root_info''][''.tag''] returned by /2/users/get_current_account doesn't indicate the type of the account; it actually indicates the type of the root currently used by the account. A "team" value there indicates that the root is a shared team root, but it is possible for an account to be on a team but not have a shared team root (which is the "updated team space" configuration in particular). Refer to the Team Files Guide and this post (linked at the top of the guide) for more information on this.

For that reason, just checking for a "team" root isn't the right way to determine if you need to use the "Dropbox-API-Path-Root" header. Please refer to the linked resources above for more information on when/how to do so.