当初とすげ替わった目的、アイズ・ヴァレンシュタインさんのことも含めて。
I'm not sure what the て-form does in this sentence.
Could it be short for ている?
No, it can't be short for ている. ヴァレンシュタインさんのことも含めて means "including things about Wallenstein"
It's hard to say something definitive without more context, but it's probably either one of the followings: