Kongou thought that leaving her core on her ship would protect her from getting spoiled by those human feelings.
Well, she was wrong.
She did feel the warmth of a true tea, she did smile at Maya playing, she did take a bite of the BBQ.

She was careful and all, but the seeds are there already. The only thing is to know wether they'll grow fast enough.

Now, we still do not know what the fog is.
We do not know why they evolved to mental models.
And these mental models crave for some humanity, their party time closed space, Haruna's crave for words and phrases etc... strange. As is they had a routine/subprocess specifically designed for them to side with humans provided they can teach them how to feel human.