I’ve always considered that texting “hehe” is a light chuckle, a “heh heh” sound; “hehehe” is more of a giggle, whether coy or creepy; and any more “he”s than that delves into witchy cackling territory.
In contrast “haha”, “hahaha”, and “hahahaha”, all sound the same in my head, and the meaning only varies in intensity but is more context dependent.
I agree on the first part, but disagree on the second.
haha is more like saying it without changing your facial muscles. hahaha is then the normal laughter and hahahaha is the crazy psychopath, let’s back away fast with more ha’ equaling to more running speed.