Island grids, characterized by peak loads in the hundreds of megawatts and transmission lines spanning tens of kilometers are in the front line of power grids decarbonization. To achieve this goal, the integration of new technologies featuring advanced and smart control solutions is essential. One such technology leap is the Grid-Forming (GFM) inverter, notably when paired with Battery Energy Storage Systems (BESS). The adoption of GFM control transforms the behavior paradigm of these devices introducing new challenges and opportunities, especially in island grids. These grids tend to be weak in terms of short-circuit level with low inertia, making them susceptible to significant voltage phase jumps when major production units are abruptly disconnected. These instantaneous deviations could trigger current and power limitations in GFM inverters and undesired trips may occur. Moreover, these transient events are accompanied by frequency deviations, demanding that GFM inverters demonstrate their capability to maintain synchronism while the power system rides through these disturbances. As an important step towards the deployment of GFM inverters, validation tests are needed to verify their full potential. This paper presents a simplified scenario aimed at emphasizing the significant challenges posed by abrupt transients to GFM inverters. The objective is to provide insight into the establishment of robust requirements.