Ok, I figured this one out. It takes names like BUILDING_ABANDONED_MINE, TOWN_NECROMANCY and CREATURE_GENIE as arguments. They need to be between quotes, otherwise the command doesn't work.

What the function returns is an array, filled with adventure map references: a name if the object has one, otherwise its generic name, like "1-210-199-AdvMapDwelling-27624". You can refer to this by using the array index. For instance:

Imp_Cruc_Array=GetObjectNamesByType("BUILDING_IMP_CRUCIBLE");

GetObjectNamesByType('TOWN') - все города на карте
GetObjectNamesByType('TOWN_DUNGEON')- все города данжена
GetObjectNamesByType('BUILDING_WITCH_HUT') - все хижины ведьм.

Похоже оно ищет по строковому префиксу типа, т.к.

GetObjectNamesByType('BUILDING_WITCH') и GetObjectNamesByType('BUILDING_WIT') дают те же результаты, что и
GetObjectNamesByType('BUILDING_WITCH_HUT').