Ah...My take on the situation (1 cent worth):
I have added a custom syntax group in my language syntax file for Vim for any personal library functions i have built (more project based then generic--i dont use a global lib-.). This way im allowed to color my syntax groups separately; (if we are talking lisp) ``lispFunc'' may show up yellow while ``lispCustFunction'' can show green.
This way, i dont have just one barrel of functions.