@exemplar
Your approach might be helpful to get the encounter in case there are no boss frames spawn initially or the shown bosses are not in the encounter's list of creatures. You'd probably better register PLAYER_REGEN_DISABLE, call IsEncounterInProgress() and check further if so. Are the x, y returns from EJ_GetMapEncounter influenced by map scale?
@Malsomnus
Combat log scanning is way beyond what I want to do with my addon. Maybe you could embed
LibBossIDs to get the mobIDs.