"The way of harmony" is a common translation, but if you ask me it's really a common mis-translation. å is used in some compounds that mean "harmony", but it doesn't itself mean harmony. I wrote a bit about that
here.
Here's what Koichi Tohei had to say about harmonizing with the opponent:
äŗä»£éäø»ćÆćåę°£éććäŗŗć®ę°ć«åćććć®éććØč§£éćć¦ććććććē§ć«ćć¦ćæćć°ćåę°£éćØćÆćåæčŗ«ćēµ±äøćć¦å¤©å°ćØäøä½ć«ćŖććććŖćć”天å°ć®ę°ć«åććéććŖć®ć§ććć
āThe second Doshu interpreted Aikido as āthe Way of fitting in with another personās Kiā. However, it seems to me that Aikido is āUniting body and mind and becoming one with heaven and earth. Specifically, the Way of fitting together the Ki of heaven and earth.ā.ā
Actually, he's correct - Morihei Ueshiba most often discusses Aiki as a process that happens within oneself, not between oneself and the other person.
Best,
Chris