SP Arty and SP AA "Type" designations switched (possibly only "American" units?)

While looking through the research tree, I noticed the "Type" or real world designations for the various research/upgrade levels for the Self-Propelled Artillery and Self-Propelled Anti-Air units seem to be switched, at least with "American" units. For example, the first US SP Arty "type" is listed in the research tree as "M13 Multiple gun Motor Carriage" though the M13 was an SP AA gun, while the second SP AA "type" is listed as the "Bishop," which was an SP Arty piece. Even the level one SP AA gun seems to have the wrong designation, as the M19 Multiple Gun Motor Carriage was a late war development, definitely after the M13, M15 and M16 MGMCs.

It's not a huge deal, but it seems like a simple fix and would keep the research tree a little more historically accurate. Also, I'm only in my first game right now as Algeria, so I can't check the other research trees (I know there's a "German" tech tree and I hope there's at least also a "Russian" tech tree), but it seems like this could also be an issue in the non-America research trees.