I found that the issue disappears the more proactive you become about your movement. Initially I had issues with the fairy lagging behind too but it turns out my Scholar was also very far behind. If your mindset is just to follow the tank and heal you end up being at the edge of maximum healing range all the time and if the Tank sprints away you are now struggling to keep up. If your mindset is instead to do the maximum damage you are always keeping up with the tank applying your dot while they move and using Art of War in close proximity once they stop. I tend to watch the enemy HP closely so I can apply a shield to the tank just before dungeon mobs die and then move with the tank seamlessly once the enemies are gone. Paying attention to the enemies will allow a proactive Scholar to move with a tank or even ahead of them within reason. There isn't any benefit to standing far behind a tank and dungeons have pretty clear linear paths so standing at the "gates" that open when enemies die is relatively simple. If you keep up as a Scholar your fairy will too. Nothing your fairy does is a massive burst heal anyway. It's all small healing over time so if that is stoping you from healing well it's time to evaluate how you're using your toolkit. Excogitation, Lustrate, and Adloquium are more than enough to hold a Tank over until your fairy arrives.