Hi Ashwini,
Talent Management components are quite different from the routine modules of SAP HCM. Since they have got their own object types, knowledge on them and their relationships with other objects plays a vital role in understanding and implementing the modules. The portal (ESS/MSS) part needs the knowledge on various iViews of ESS. To add to the hardships of an HCM Consultant (kidding...
) UI5 came into the picture.
Whether the HCM consultant does the above quoted activities or a developer is needed depends on the project and consultants themselves. When I first implemented ERC, it went on brotherhood. My portal consultant would educate me on various services, train me how to test them. When I first implemented Objective Settings and Appraisals, my ABAPer would find out the tables where the data was getting stored and gave their list. When there were errors in the iDocs, while there was data transfer between ECC and ERC systems, my XI consultant would check what went wrong!
Make it clear to the entire team that you are new to these areas. Be nice to the technical consultants and get their help. You will learn by yourself!
Wish you all the very best!
-Sasi