You are talking about combined conditions created inside of the Visionaire Studio editor? Actually, I've never tried querying a combined and/or condition with Lua script before. It's simple enough to query multiple instances of conditions with Lua script though, so just query the two conditions or as many conditions / values as you like with Lua script directly...
if Conditions["x"].ConditionValue and not Condition["y"].ConditionValue then
-- do something
end
if game.CurrentScene.SceneConditions["x"].ConditionValue then
-- do something
end
if game.CurrentScene.SceneObjects["example"].ObjectConditions["x"].ConditionValue then
-- do something
end
... I guess you get the idea! You can create some fairly complex if queries with Lua script compromising of various different query types from boolean, to integer, to float, to "string", etc.