Can I exit STOP2 mode by going HIGH on the IRQ pin (If I have configured the IRQEDG = 1) IRQ is rising edge/high-level sensitive.
The manual on p.43 says
22.214.171.124 Exit from Stop2
Exit from stop2 is performed by asserting the wake-up pin (PTA5/IRQ/TCLK/RESET) on the MCU.
PTA5/IRQ/TPM1CLK/RESET functions as an active-low wakeup input
when the MCU is in stop2. The pullup on this pin is not automatically
enabled in stop2. To enable the internal pullup, set the PTAPE5 bit in the
port A pull enable register (PTAPE).
p.47 says "Assert zero on PTA5/IRQ/TPM1CLK/RESET" to Transition from STOP2 to RUN
Then p.93 says
126.96.36.199 Pin Configuration Options
...As an IRQ input, the user can choose the polarity of edges or levels detected...
and p.98 even has a register for the Edge Select IRQEDG