Using a reliable pt and having decent skills with them is very useful when getting away from these monsters. Stamina is essential to getting away so when you can hear their elemental attacks just roll left or right taking advantage of their terrible turn radius and most of the time totally ignoring any of their damage. Last thing is fly through trees or places where the wyvern would get distracted/stuck, like in Val where there's packs of mammoth that they will aggro onto instead of you