The question is ... why are the roms for the other devices still on android 6 and the version 8.2.1.0 for the Mi5 on android 7?
Is this perhaps again an unofficial version like the 8.1.9.0
Did you make a factory reset after flashing 8.1.7.0?
I am unsure because there is no 8.1.7.0 china stable. What kind of version is the xiaomi.eu 8.1.7.0?
Latest china stable is still 8.1.6.0...is the xiaomi.eu 8.1.7.0 homemade by xiaomi.eu?