С GNU sed для сокращения \ s / \ S для пробела / не пробела и -E для включения ERE:
$ sed -E 's/\s+(\S+)\s+(\S+)$/,\1,\2/' file
Somename of someone,1234,7894
Even some more name,2345,5343
Even more of the same,6572,6456
I am a customer,1324,7894
I am another customer,5612,3657
Also I am a customer and I am number Three,9631,7411
And I am number four and not the latest one in list,8529,9369
And here I am,4567,9876
и функциональный эквивалент с любым POSIX sed:
$ sed 's/[[:space:]]*\([^[:space:]]\{1,\}\)[[:space:]]*\([^[:space:]]\{1,\}\)$/,\1,\2/' file
Somename of someone,1234,7894
Even some more name,2345,5343
Even more of the same,6572,6456
I am a customer,1324,7894
I am another customer,5612,3657
Also I am a customer and I am number Three,9631,7411
And I am number four and not the latest one in list,8529,9369
And here I am,4567,9876
или с любым awk:
$ awk -v OFS=',' '{x=$(NF-1) OFS $NF; sub(/([[:space:]]+[^[:space:]]+){2}$/,""); print $0, x}' file
Somename of someone,1234,7894
Even some more name,2345,5343
Even more of the same,6572,6456
I am a customer,1324,7894
I am another customer,5612,3657
Also I am a customer and I am number Three,9631,7411
And I am number four and not the latest one in list,8529,9369
And here I am,4567,9876