How flexible must a transformation approach for variability models and custom variability representations be

A plethora of variability modeling approaches has been developed in the last 30 years. Feature modeling approaches are probably the most common and well-known approaches. All existing variability modeling approaches have their benefits and drawbacks and have been shown to be useful at least in certain use cases. Nevertheless, industry frequently develops their own custom solutions to manage variability because they struggle picking an approach from the (still growing) number of modeling approaches available. Therefore, we work towards a transformation approach, which enables researchers and practitioners alike to compare different (custom) variability modeling approaches and representations and switch in between them at least (semi-)automatically. In this paper, we discuss ongoing challenges for the transformation approach regarding the implementation of the transformations and the expected flexibility of the approach. We present our research agenda towards a flexible and adaptable transformation approach for well-known variability modeling approaches and custom variability representations used in industry.