No you didn't, Xiaomi EU is much slower than original ROMs, reason why I personally stick and recommend to install official global ROM if you don't want china ROM
The issue is related to idle battery consumption, obviously if you want to improve that you got to disable many thing going on in background and activate Ultra battery saver mode when you idle to maximize SoT
Into miflashtool go to settings and delete the checkpoint string, then reinstall any official ROM let the process complete the phone will reboot automatically at the end
Did you renamed the image into "twrp.img", sorry asking but I need to rule out common mistakes.
you use the windows cmd prompt right? I hope you are not using poweshell
I don't understand when this issue appears. When I go into twrp to insert the pattern I just need to press it longer and it goes fine. Did you try to insist?