I am positing that any "entering" is by nature an invasion.
You're going into a place you're not intended to be, and it is traumatic by nature because you have to break through natural barriers to get in.
We haven't seen any such interactions described as one person "opening the door" for another, or the person being "entered" doing anything to facilitate or bring the other person in. It's always the other way around -- the person doing the entering is doing something to get in.
As far as what info the books gave us, entering by itself pose no harm. Rewiring things inside is the problem.
in book 13, Harry mentioned that he and Molly practiced entering each other's mind. Nothing bad came out of it.
Entering another's mind without permission seems to be harmless also. Molly did that to Harry in book 10 and to Luccio in book 11. It is however forbidden by the council's laws of magic. But as far as I can see, just entering another mind cause no arcane damage. It might cause psychological damage, but not arcane damage.
Influencing another's mind is trickier. Influencing is one step closer to rewiring, but the books gave us examples where such influencing is either accepted practiced or tacidly allowed.
Spells of suggestions are the most common examples. Even Harry uses it to ward his temporary hideout in book 11 and Morgan himself accepted the use of such spells. Veils also influenced people's mind" "Nothing going on here", "Just a background" and so on. Suggestion, distraction, seduction, temptation are all influencing minds, and to a certain extent such things are sort of allowed.
Which is why I can accept love potions as legal in the eyes of the 7 laws. Apparently influencing another's mind is considered all right to a certain extent.
It is all depends on how the wizard achieve his or her goals. Illusion magic that directly input images into another's mind is illegal, but use hollomancy and similar results are considered legal. Hypnotizing a woman to be a seks slave is a big no no, but magic or potions that cause sexual overdrive on the physical body or cause addiction could make a woman into a seks slave just the same and I think the council's 7 laws does not cover that.
Same with the first law. Burning someone with fire magic is a capital crime, but immobilize someone with air magic and than shoot them dead with a gun is legal.
What's the point for the 7 laws then?
The point is damage control. Practically speaking, it is not that the council does not want to include the concept of justice in it's laws, but I think they simply does not has the strength to enforce such a law.
It is said that there is about 5000 wizards in the world. Practically 5000 super humans.
You simply cannot constrain such a power. If you restrict wizards too much, they'll rebel. There'll be a war.
Merlin's 7 laws of magic is about the most the wizard community could tolerate, and I strongly suspect wizardkind initially accepted such a rule because Merlin is simply too powerful to defy openly at the time.