I can see what you are saying about Pensylvania Avenue deflecting upwards from the 23.5-degree angle becoming 19.5 degrees to meet the CB and after it leaves the Whitehouse; when before the WH the avenue is 23.5 degrees.
(Also, despite what you say on your webpage, I am also familiar with the significance of 19.5 degrees - via the work of Hoagland).
I can see why that discrepancy would pose a problem, and going by everything else it is a bit of a puzzle why everything else should fit when this part of the picture doesn't so well. Perhaps you have your own answers on this.
Anyway, when first discovering this, it wasn't really a problem for me, because as I said, I went by the symetry of the whole design where most of these avenues are at the angle of 23.5 degrees, and the triangle (pyramid) still fit quite well on the map despite this deflection on a map of several sq miles which may have been for an important reason, and so for me this was the picture that was intended.
Another thing, 'fig 6' on my webpage was put together in 2002.
During 2005, I alerted Don Barone to the fact that there are numerous references to the angle of 23.5 degrees in many 16th, 17th and 18th century paintings and other sources, often along with the angle of 52 degrees.
After some research of his own into this, Don found that the avenues leading off from the White House are at this angle and sent me an image. It was then sometime after this, that I saw how this diagram that I created in 2002, fit the Washington Map.