This has come up before on this thread but the legal definition of a distributor is someone that buys and resells a product and he will then will assume full responsibility for the validity of any CE marking as is described in the various references quoted in the thread.
The legal definition of an agent is an adviser, usually to the seller, who does not take any part in the commercial transaction. An agent would have no responsibility for the validity of the CE marking in any other field e.g. Machinery Directive. Only the seller would be responsible.
Whether a broker is a distributor or an agent depends on their agreement with the seller and the documentation used for the sale. As I have never bought or sold through a broker it would be interesting to see some broker documentation.
See https://www.aqueductmarina.co.uk/wp-content/uploads/Vendor-Agreement-Contract-.pdf
The broker makes it very clear they are only acting as agent.