The English version of Eyjafjallajökull is Eyotfellicle

An interesting post here on the linguistics subreddit shows the less than obvious but still present connection between the Icelandic Ejyafjallajökull and English. What looks completely foreign at first glance is actually cognate with the following:

Eyja - Eyot or ait, a type of small island.
Fjalla - English fell, a type of mountain.
Jökull - cognate with the -icle in English icicle.

So perhaps those stressing out about how to pronounce the mountain should just resort to the anglified eyot-fell-icle, no different than Caesar to Kaiser or William to Wilhelm or any other way in which other languages take cognates and modify them to suit their own tastes.