Yes, without a working TWRP at encryption level, the only solution is to trip fstab as we were doing before.
That perfectly work on android 10.
Already Checked on MI8 and MI8SE.. May be many more people can confirm it as well.
No hope to have an updated TWRP release for these "old" phone model.
Thanks. I enable encryption by modifying fstab.qcom file manually. Now the encryption works.
(I also checked the thread you give, and create my fencrypt.zip for MIX2S. Maybe it can be used for the next time)