As a translator, she played a key role in mediating between the Chinese and foreign parties.

mediating 是动词 mediate 的现在分词形式。mediate 由词根 medi-（表示"中间"）和动词后缀 -ate 组成，意思是"居中调解、斡旋"。在句中表示"在中外双方之间进行沟通协调"的作用。