Status of Derived Business Transaction (DBT) is handled here:
IMG -> Financial Supply Chain Management -> Treasury and Risk Management -> Transaction Manager -> General Settings -> Accounting -> Derived Business Transactions -> Control of Processing of Derived Business Transactions
Right now you have settings like this: Online + Same status - This means that all DBT will be used online and will have the same status of the original flow ( original flow is posted and DBT_B001 is really posted as we see). But as concernes DBT_E001: this update type is used when you post Final Repayment flow. This update type is only clear Balance value component so this transaction is no longer can be used and it is not needed to make any posting for this DBT.
P.S. The status of error is green - it means you don't have to warry of this error!!!
Generation/posting of derived flows - this article shows you the other steps if you have other parameters in "Control of Processing of Derived Business Transactions"
As concerns the second error - use tr. KA01 to create cost element in controlling area AD01 starting from the begging of this year. Cost element type = 1.