Hi
Sorry I am still confused
the PTA0 does not have IRQ function, it has KBI
The PTA5 has IRQ, but it does not have KBI
please check the attached

Then if I am understanding properly you can set the IRQ on the PTA5 with the vector interrupt 2

and you can set the KBI on the PTA0 that has the vector interrupt 18

With this you will have 2 vector interrupts, 2 status and control register.
The KBI has a higher priority.
Regards