I owned a 2016 Civic with Sensing that I drove for 74,000 miles. In my experiences that car reacted exactly the same at my Clarity does with ACC and LKAS. So I feel it's just how Honda's system works...not Clarity exclusive.
The only difference with Clarity I will comment on is the anemic acceleration after you get into clean air and the car is ready to recover speed....but this is only an issue in Econ mode -- it accelerates at a better pace in non-econ or Sport mode, so that one quirk has nothing to do with the Sensing package.
All that said, I have never had either car brake hard "for no reason." I have seen it over-react (in my opinion) to other cars in its path, cross traffic, cars in adjacent lanes running very close to or drifting over the center line, and even oncoming traffic on curved 2 lane roads has triggered a beep/brake pump event. But the car had a reason...it saw "something"...as did I...though I knew darn well that the "something" it saw was not a threat, it hit the brakes kinda hard temporarily and almost instantly released them after quickly realizing "oops..no threat" -- which is/was an annoyance I admit, but it never made me feel unsafe and it never did anything silly like bring the car to an abrupt stop. And I did fully understand why the car pumped the brakes, even if I disagreed with the logic to do so.
I also really don't think it's a good system to even bother engaging in stop and go traffic. So I guess I can't fully describe how the car would react in that circumstance since I never use it when traffic is like that. The way it drives then annoys me -- I can certainly do better. So in my opinion it's best used for interstate or highway driving at speed, following other cars and keeping pace with traffic. And works pretty well for that, with certain occasional annoyances and glitches that I fully acknowledge exist.
The system does not replace driving the car and being attentive at all times. It's just an anti-fatigue assist system.
