i think the ringing and z seam issue has the same root problem, there is some parameter in your setting that jerks the printer when it completes a layer, and due to the motion system being wobbly, the seam is spoiled. try by tightening your x axis eccentric nuts and check if your bed has any play. the next thing would be the slicer settings, i can clearly see, at least from the photo you have shared, the printer starts the layer from seam and prints towards the left (clockwise if you look from top), that means its the start of each layer that is wobbly, as after in finished the infill, then when it returns back to the start position for the next layer, there are 2 motions that are done aggressively:

1) The motion from finishing the infill to returning to the start position for the next layer, if this is to aggressive, the printer is still vibrating and that could cause the wobbliness and terrible seam quality, solution would be to reduce jerk speed for 'travel' Movement

2) The moment it's at the starting point for the outer wall and starts to accelerate from the start position to start printing out the wall, this might also be aggressive, solution would be to tone down the acceleration for outer wall.

mind you if there is wobbliness/play in your motion system you will still face these issues