Thanks for your patience and linking me this guide. Your work is awesome!
I decided to first take a look on the sleep problem and followed everything in the guide. Used the script to create a ssdt.aml (with beta directory because of 10.12) and moved it to the EFI/CLOVER/ACPI/patched/ directory. I also created in Clover with F4 my original DSDT files and copied then from the /origin/ folder. Afterwards I followed your guide and used the terminal to decompile them to .dsl files. I modified these and saved them as .aml files.
Afterwards I applied the DSDT patches:
[bat] Lenovo X220
[igpu] Brightness Fix (Haswell)
[sys] Fix Mutex with non-zero SyncLevel
igpu] Rename PCI0.VID to PCI0.IGPU - on DSDT.dsl, SSDT-1.dsl, SSDT-10.dsl and SSDT-13.dsl.
Everything is working fine now around the CPU, Brightness etc. Except the sleep mode. The computer gets without any problems into the sleep mode (LED is even blinking) but when I would like to wake up the machine, I just hear loud beeping and nothing happens. I cannot see my mistake and I am looking all over the boards for solutions. I will keep looking and update this thread.
If somebody has an advice or hint what to try next: do not hesitate to tell me
Edit: Beep characteristics: 4 Long beeps - BREAK - 4 long beeps - BREAK - 4 long beeps - Black Screen and nothing happens