I suppose you are talking about functions in generated code.
Which component and which API function you are talking about? Which device??
Yes, it is generated code. I'm trying to use ADC_SAR_SEQ_EnableInjection() on a CY8CKIT-043 (4200M). I've declared the library.
Depending on the configuration of the component some parts of the API are available or not. So you need to look there. (In your case you need to enable the injection channel)