If you using ROM provided by me, hope you aware, that you can use MoreLocale to get translated into your preferable language all but settings/system messages which used not so frequently.
https://xiaomi.eu/community/threads/fastboot-rom-miui-8-9-los13-with-gapps-root-and-some-other-stuffs.34148/
Camera not working. Probably you will get jumping battery level.
Those, who flashed latest published China dev based and followed instruction about Updater, should not have any problem applying latest OTA. Tested on myself.
Find 8.5.1 Stable MIUI8 for fastboot and do a complete flash using batch file provided. Maybe this will help. Then flash over latest after initial setup.
I suppose, problem was in Data. When you were in TWRP it was necessary to wipe Data partition. I'm not creating Data image, so you're not flashing it. So now you're on LOS13? I saw, that guys used Xposed. You can try. Maybe I'll include it in next release.
OTA - no. I have no idea if guys will continue and for how long time. I got some small troubles like a bit strange WiFi behavior, non working sound regulation from headset and so on. In total ROM is fine. The only thing I definitely don't like is error3 (unlocked bootloader). But it's nothing to...