My plan is using a Grounded Theory design and a semi-structured interview as instrumentation. I'm wondering if you could tell me your suggested design, method, instrumentation and participants or any other help.
Grounded theory design seems like a good idea especially if it is a 'new' topic within the field. I would suggest the following:
Use theoretical sampling, bearing in mind the access issue, i.e. how are you going to access the participants, e.g. through gatekeeper(s) or snowballing method. Using theoretical sampling will help with generalisability of the findings to a bigger population.
As it is a data-driven methodology, make sure that you undertake constant comparison and iterative approach
Consider deviant case analysis, to ensure that you account negative cases and avoid cherry-picking.
Linguistic imperialism is a highly political concept and probably works in a grounded theory approach as a pre-concept what is not at all helpful. I would advice to search for more concrete situations and behaviors and discuss them with concerned people and let emerge concepts and basic social mechanisms through research.