Contains an unknown symbol and will be ignored

[prodnet]

Where is the error, I have the same error message no matter what options I use ?!

./createNG --iPwdList pw.txt
WARNING: Either errors or warnings occured. Enable print warnings to see these.

./createNG -w --iPwdList pw.txt
WARNING: nGram(s) in line 11743008 contains an unknown symbol and will be ignored.
WARNING: nGram(s) in line 11743141 contains an unknown symbol and will be ignored.
WARNING: nGram(s) in line 11743160 contains an unknown symbol and will be ignored.

[prodnet]

Please let me know.

[m33x]

I don't see any error message here. I see a warning only. You can change the verbosity of OMEN to find out what the issue is. I guess you forgot to filter your input file for ASCII only characters. Learn how to do this here:
#4

[m33x]

I don't know.

Try to rename the file pw_pw_ascii_16.txt to password-training-list.txt or input.txt

Also try --verbose and --printWarnings to get more details.

[m33x]

Looks good so far. What happens if you start the enumeration after your training?
e.g. ./enumNG -p -m 10000

[m33x]

Sorry but this is not a support forum.
OMEN is a scientific proof of concept, not a hash cracking software like hashcat / JtR.

Regarding your question:
Alpha values, go ahead and read the paper:
https://arxiv.org/pdf/1304.6584.pdf