Thresholds for traffic alerts and for traffic display are two different settings, but they're in the same menu area:
Menu > Setup > Traffic Alerts > Set Alert Thresholds: Affects when you get popups alerting you to nearby traffic
Menu > Setup > Traffic Alerts > Distance Visibility / Vertical Clearance Visibility: Affects which traffic targets are drawn on your moving map
Re: the Stratux AHRS chip, realistically, you can only expect so much from a $15 part, but it can and should function better than what you are describing. You say you have "calibrated" your Stratux, but I can think of at least three things someone might describe as "calibration", and they will do different things and not all of them would address your problem. Exactly *how* are you calibrating?
If you haven't tried this, I recommend it. This suggestion came from Chris Young (the Stratux developer) when I was having trouble similar to what you describe. First, set your Stratux on a level surface and don't touch it. Power it up, then connect a device with a web browser (phone, tablet, or laptop) to the Stratux wifi network, and use a web browser to log into the Stratux user interface at http://192.168.10.1/. In Chris' words: "There are calibration values that are measured from the gyro when the unit is first started up. If the unit was moved during this first-start routine, it could potentially cause this issue. Try plugging in the Stratux, setting it level, and then go to the 'Settings' menu and 'Calibrate Gyros'. This is a different function from the 'Reset/Level' function on the GPS/AHRS menu."
I have only had to perform that "Calibrate Gyros" action one time. It has functioned well ever since.