I cannot find sirens number 2, 18, and 19. However, siren #19 sparked my curiosity because the location listed for that siren in the document was "Southern University." Southern University and A&M College has a Whelen WPS-2910 located at coordinates 30.524525, -91.193308.
Dropping down into street view reveals that the WPS-2910 had an old ESC-864 style cabinet, which was upgraded to the newer ESC-2020/ESC-2030 cabinet sometime between 2008 and 2016.
As a side note- ALL THE WPS-4008 sirens in Baton Rouge have the ESC-864 style cabinet.

Is is out of the realm of possibility that this WPS-2910 replaced a WPS-4008? Especially with the fact that no WPS-2900 series sirens shipped with the ESC-864? That would solve the mystery of Siren #19 at Southern University.