Because of the special meaning of / as first character of a line (/L1, /C1, /Delimiters, ...) words starting with / must be on a line starting with //. For example to highlight a single /, it must be defined at the color section as // /.

And the reason why non of your error "codes" work is, because they are all no single "words". All characters at your error list are also word delimiters, defined in the delimiters line. So for example /& are interpreted as two "words".

To get your error codes working, you have to remove % & ( ) / ? | from the delimiters list. But this also means, that you always have to write a space before and after these characters in your source code, so that the space is now the word delimiter. I think, that is not really practicable.

Last tip: you must alphabetically sort the lines with your words. Example:

/C6"Errors"
%%
&/
)%
)(
)?
// /& //
||