I don't know what problems you always have with XIAOMI phones
I use (look after others) 3 different Xiaomi phones.
The oldest Redmi 3s with Android 6.0.1, then a Redmi 4x with Android 7.1.2 and a Redmi 7 with Android 9.
Next to Primo there is also Nextgen from NNG (iGO World), Basarsoft, Israel, Israel Gift and for testing on the Redmi 4x also Avicsync and Motrex.
For all without "linked_root_list" in the sys.txt, secondary_root_path is set to "igosd"
No more "witchcraft" in sys.txt, everything just standard.
No problems on any of the devices.
I also use similar configurations on a Huawei Mediapad T3 10 with Android 7 without any problems.
In my opinion, the biggest problem among users is the play instinct ...