LOS13 ready for download. Note, TWRP will be flashed and error 03 will persist. I tested ROM myself and all working fine. No random reboots.
Camera not working!
Ha! Just got to know, that due to Updater bug, it's downloading OTA and then full ROM. So if you don't want to wait, flash over my last version, download update, flash smallest size via 3 dots.
I'll update MIUI next week. Will try to publish LOS13, based on Android 6 not 7, today evening. We will never been moved to 7. No Intel drivers. 6 is absolutely last step.
There are no ROM's with Android 7 on our device. But, next week, I'll publish LineageOS 13 based on Android 6 for fastboot/toolbox, made by tank0412. I'm testing now. Looks nice.
Have a look into archive for 8.5.1 for China based ROM provided in initial post. I think recovery.IMG will be there. If not - download original fastboot China based ROM 8.5.1 and extract recovery from there. Then take toolbox, copy recovery image you would like to flash into RECOVERY folder and...
What exactly you mean under "multitask"?
If it's about multi language, then only one option is MoreLocation that already included in my ROM. It allows you to get all but settings to quite a lot of languages.
7.9.14 was actually not an OTA, but full release. That's why you loose everything. My version will be tomorrow evening. If you could, just stay with existent 7.9.14 till tomorrow and then flash over.