I've used the ask/tell thing and added a script to move item "Ezshuni's Key" from parent "Ezshuni Orian" to "Player" (It needs to go in the inventory, that seemed most appropriate) and then move object "Ezshuni Orian" to "Outside the Temple of Light".

She also says something, obviously

I believe that this is where the problem lies as it was the thing I did after the last working test. However, I'm getting this error message when I launch the game.

System.Exception: Function not found: 'msg'
at AxeSoftware.Quest.Scripts.FunctionCallScriptConstructor.Create(String script, Element proc)
at AxeSoftware.Quest.ScriptFactory.CreateScript(String line, Element proc)
at AxeSoftware.Quest.ScriptFactory.CreateScript(String line)
at AxeSoftware.Quest.Scripts.FunctionCallScriptConstructor.Create(String script, Element proc)
at AxeSoftware.Quest.ScriptFactory.CreateScript(String line, Element proc)
at AxeSoftware.Quest.LazyFields.ConvertToScriptDictionary(IDictionary`2 dictionary, ScriptFactory scriptFactory)
at AxeSoftware.Quest.LazyFields.Resolve(ScriptFactory scriptFactory)
at AxeSoftware.Quest.GameLoader.ResolveGame()
at AxeSoftware.Quest.GameLoader.Load(String filename)
at AxeSoftware.Quest.WorldModel.InitialiseInternal(GameLoader loader)

Could you please tell me what the error here is?

Never mind, I used the backslash before the quotation marks in the Print Text sections. Deleting those seems to have fixed it.