Interesting work.
Thing you need to keep in mind:
self-propelled artillery is allot more difficult to kill. They can take a direct hit and survive, they can move out of the way and are harder to kill with offmap.
Super charge round not only have allot more range but also are on different CD of the normal barrage. Sexton can fire almost continuously with it.
The barrage have different CD and the units have different vet bonus so the comparison at different vet level will probably give you different results.
Both Royal arty commander and infatry commander have access to stock reckon pass and offmap that can kill a Lefh.
In sort I do not really agree with the suggestions.
Pretty much +1
Mobile artillery has the advantage over static as it can constantly re-position.
Would like to see counter battery on the Lefh changed for something that requires even the smallest amount of micro.
Otherwise artillery isn't in a bad spot at the moment.