If someone might feel this useful... Since new Xiaomi.eu version requires TWRP (no fastboot version anymore) tried to use the TWRP for DITING.
According to the playstore app, it was a A/B version.
fastboot.exe boot twrp.img did not work. Resulted on this.
TWRP "Failed to load/authenticate boot image: Bad Buffer Size
That's the error that appeared, so reading guides, since it was A/B device, it shouldnt let flash the stock recovery... To my surprise it did flash but phone remained on Fastboot screen boot loop.
To fix this... flashed fastboot xiaomi.eu version for DITING (12T Pro) and then it let me enter to recovery (TWRP).
Then had to format data so SSD would appear, transfered ROM and flashed ROM.