Wajk, why you don't try to implement thememanager from this rom http://4pda.ru/forum/index.php?showtopic=456979, it doesen't need any mi credits or miui acount login for changing themes?
Look at this thread at XDA forum http://forum.xda-developers.com/nexus-4/development/rom-miui-v6-kitkat-t2691163
MIUI v.6 with RIL working, on Nexus 4.
http://imageshack.com/a/img845/4905/i2gr.jpg
It is very possible that your network is 3g only, so when you put in 2g your phone , you are automaticaly rejected from network. Just try with other phone to switch from 3g to 2g on same network, you will find the answer.
Here is MIUI-3.9.13.LianYi . You could use google better. I reuploaded from baidu to mega:
https://mega.co.nz/#!cFtkGLhZ!eJtqcTFPlSAStcpB6LkbnH7KaO1rO9oAewk4Ku-2QeU