It helps to try all sorts of placement. Proper location of a speaker is largely a random hit or miss thing and even a movement as small as 1/2 inch can make a huge difference if you happen to be moving into or out of a strong mode.
For your particular issue, I would suggest working with the rake angle first (the backwards tilt). Many speakers are not actually meant to be heard with the tweeter at ear level. It may be the case that the ideal position, for both correct frequency balance and image placement is on a different axis.
It might seem counter intuitive, but, the ideal placement may be with the speaker lowered in height and tilted back a bit. That often raises the height of the center image. I am not saying that is going to be the answer, rather, I am saying try everything, including lowering the speaker to raise the image height.
For your particular issue, I would suggest working with the rake angle first (the backwards tilt). Many speakers are not actually meant to be heard with the tweeter at ear level. It may be the case that the ideal position, for both correct frequency balance and image placement is on a different axis.
It might seem counter intuitive, but, the ideal placement may be with the speaker lowered in height and tilted back a bit. That often raises the height of the center image. I am not saying that is going to be the answer, rather, I am saying try everything, including lowering the speaker to raise the image height.