Interesting break down. The image you included is a super hard case to handle since 50% of the image is over exposed and 50% is underexposed. If the exposure time was any higher the right side would be totally blown out. This is a limitation of the camera and the optics. Higher quality gear will capture more dynamic range and give more usable images. We have been seeing some really nice images coming out the Inspire Pro since adding support. An added benefit of the Pro is that you can use narrower FOV lenses (we like the 15mm stock one) because it limits the parallax and makes it so less of the images get thrown away due to extreme angles. 94 degrees is a really wide FOV.
We use the standard modes that are provided by DJI in their SDK and they should align pretty well with how they function in DJI Go. There shouldn't be any difference between the auto from before and the auto now other than as spring is coming there is more light available and you are more likely to be overexposed with harder shadows.
You might want to go with Shutter priority and the exposure time set at 1/320 or so since you know where your cutoff for the images working is. The problem with that is that the ISO adjustment is more likely to saturate the image. There no way to set an exposure time floor in Auto mode.
The longer exposure times getting streaky is why we have added the in-air speed reduction if the prevailing light conditions won't allow full speed flight.
A lot of this is really just going to come down to physics and basic photography tradeoffs. I know you are way up north so solar noon doesn't provide a huge difference in shadow lengths but every little bit helps.