Hello Eric,
I debug your project, find the issue.
In function PINT_Init(PINT), disable all the PINT interrupt, and clear PINT callback array, so in core1 project call this function, the interrupt in Core0 can't work.
So please in Core1 project you can call CLOCK_EnableClock(kCLOCK_Pint); instead that function, I test on my side, it can work, attach it for you.
Hope it helps,
Alice