You can use /tellraw or something similar for colored messages, you can always implement this with other things, I think /blockdata works too. Not such a big command block nerd.
Example /tellraw @p ["",{"text":"Su","color":"black","bold":true},{"text":"per","color":"blue","bold":true},{"text":"Cow","color":"black","bold":true}]
[0x7FFC1E62F2B0] ANOMALY: meaningless REX prefix used [0x7FFC09B14450] ANOMALY: meaningless REX prefix used [0x7FFC09B190E0] ANOMALY: meaningless REX prefix used
It's most likely a problem If you are using a plugin.
