The table of available ROMs is incorrect, it shows that the Mi 8SE has Android 10, but there is currently only stable Android 9
There is weekly Android 10 but no stable Android 10 (for Mi 8SE)
Updating my Mi 8 SE unrooted my phone and I couldn't boot into recovery (stuck on Unlocked screen). I reflashed TWRP-3.2.3-1227 using the same command you used and was able to successfully boot into it.
You can root the phone if the data partition is unencrypted, go to Advanced > RM...