Answer ... If the parties have agreed upon certain rules regarding the allocation of costs, the tribunal will be bound by, and will decide in accordance with, those rules. Otherwise, the tribunal will determine the costs that each party to the dispute must bear - including the amount that was necessary in order to present the party’s case - by taking into account the circumstances of the case, and in particular the outcome of the proceedings (Section 1057, paragraph 1 of the Code of Civil Procedure). The default position under the German Arbitration Act is that costs follow the event, so the losing party must generally reimburse the winning party for its legal costs.
Answer ... The parties are free to agree not only on the procedure, but also on the criteria for the allocation of costs. There are no explicit limitations provided by the German Arbitration Act.