I still don’t see anything from the first map other than regions more advanced culturally, like Germany and Italy were also centers of printed book publishing.
Note that the symbolism of colored dots prevents the map from expressing the fact that a center prominent, say, in 1460’s, like Venice remained prominent in 1670’s and beyond as well.
The second map is from a different time frame, and it does show that mass literacy spread to “cold” countries first.
So would you summarize: “hot” temperament likes the image and “cold” temperament likes text? And that further, “hot” temperament is Catholic and “cold” temperament — Protestant?
I wouldn't quite put it that way in those terms, although I think that hints at an underlying truth. I would think a more precise summary is that for roughly the first 1500 years of the Church (and by that I'll include both Roman Catholicism and Orthodoxy), overwhelming rates of illiteracy meant that the laity took their instruction in the Bible from literate clerics. This instruction was augmented, enhanced and reinforced through the use of visual cues: icons, stained glass, statuary, etc. For those unable to read the Scriptures, these symbols, coupled with the learned instruction became the source of faith knowledge for the laity. Needless to say, great import was placed upon them.
Now, completely regardless of whether one considers the 15th Century advent of the printing press and the 16th Century reformation to be causally related or entirely coincidental, literacy grew much more rapidly in areas that embraced protestantism. The new protestant laity had far less need for image based instruction as both the literacy of the laity, and the availability of the printed word would have allowed the protestant to merely "follow along" with the readings at the service. Hence, the role religious imagery played in the protestant churches would have become far less important and indeed eventually marginalized.
As I indicated above, I'm not suggesting this as an all encompassing or comprehensive explanation of Newman's observations as I would be the first to concur that there were many other factors at play; however, I think it's significant enough of a factor that it can't be ignored.