If I create a new implementation for a user exit, finding the CMOD project name months later is not a problem (if unsure, I just check the content of my transports). But when I modify the existing user exit, and know only the ABAP include or function name, SAP does not provide any standard function to find the customer enhancement, for example, in case I want to disable it temporarily. And as it often happens, we have to look at the database tables.
SAP user exits (enhancement names that we see in SMOD transaction) are all stored in the table MODSAP. The field NAME contains the enhancement name and the field MEMBER contains the name of the function module that will be called if the customer enhancement exists and is active. The customer enhancement projects are stored in the table MODACT. There, the NAME field is the name of the project and MEMBER is the name of SAP enhancement (that from the MODSAP).
So, if you are in some include, you can use where-used-list to get to the function module name. Then you find the SAP enhancement name from the MODSAP by supplying the function module. And finally, you find the customer enhancement projects by querying the MODACT with the SAP enhancement in the field MEMBER.