Hello,
For example, we can see that reading /executing code during an erase/write operation is not allowed on the same flash block in the RM rev 12.1
So, the program phrase functions and erase flash sector functions are a test of "simultaneous flash operations" itself because it cannot run in the same flash block which are being erased/programmed.
For example, in the attached simple test code, you can see these functions which are placed in RAM to avoid executing code/reading from the same flash block during write.
I hope it helps.
Best regards,
Diana