Hi Adithya Kiran
So, For the 8E1 and 8O1 cases you are checking PARITYE from UART_ED register, witch is correct, not problem here. About 8N2 I don't fully understand what are you trying to implement, Are your talking about configure your MKM34 as 9N1, but only receive an 8 bit with parity enable data? and detect the parity in the ninth bit received? Could you clarify your method?
NOTE: If you configure your MCU as 8 bit mode, R8 bit in UART_C3 register will not change because MCU will not load any value here, so, it will not represent the stop bit nor the parity bit.
Have a great day,
Jorge Alcala