Question JB ROMs from KK

I have a really strange issue, I'm on KK with TWRP installed. All KK based ROMs are working perfectly without any problems. But when I try to install TWRP for JB (Issue was also there when I was on B125 with this unlock code) or a JB based Custom ROM my phone vibrates all the time and I'm unable to do anything with it. My thoughts of this is that my phone is still kinda locked on JB but unlocked on KK, so for a completly working JB ROM I would have to downgrade to B118 or B120 right? But now I found a Custom ROM based on JB that works on my device its MIUI V5 by @greatslon ! And I'm wondering why this is working but all others don't, maybe anyone can help me a little bit
Huawei Ascend P6 - Perfect Phone