Start with the text(s) you intend to analyze. The text subjected to study will steer you in the direction of the proper theory not the other way round.
Utilizing a theoretical framework is advised for research. As you pointed out, it would be best to use Nozizwe and Ncube's loss and gain theory in the case of translated Punjabi text. Given the lack of research on indigenous languages, it might aid in promoting the local culture as outlined in the "gain" feature of the theory. From a linguistic standpoint, it also makes the target text flexible and usable in any social context.
Khubaib Ur Rehman Please contribute to the discussion with your ideas.
Depending on the type of research you are conducting, you may need to combine theories from different areas to strengthen the analytical argument. For example, if you are working with discourse adjustment in contexts of social dynamics in different groups, you may need to combine critical discourse analysis (van Dijk) with social representation theory (Moscovici). I also recommend checking out some studies on social representations of language (Bernstein).