Hi Ben,
what version of TI-RTOS are you using? There is a bug id (SDOCM00108100) assosioated to the ENV.h to have the need to define each individual MSP430 device removed.
You should be able to just add a your device into the ENV.h's #if statement as such:
#if defined(__MSP430F5529__) || defined(__MSP430F5419A__)
After adding the MSP430F5419A into the MSP430DEVLIST you can rebuild the drivers:
c:\ti\tirtos_msp430_2_00_01_23>..\xdctools_3_25_04_88\gmake.exe -f tirtos.mak drivers
I've tested this with TI-RTOS 2.00.01.23 and it worked for me.