I'm not an editor expert, but I believe that Civ3Edit must be used with Civ3 version 1.21 to CREATE your scenarios, and then I think you can PLAY them on 1.29. But normally Cv3Edit crashes on launch if you try to use it with 1.29, so I don't know if this is your mistake.
Brad can probably tell you where this message comes from.
[EDIT] I just realised you said you have version 1.29g of Civ3. Since there is no "g" variant of Civ3 1.29 for Mac I can only guess that you meant to say you have version 1.21g, in which case please ignore all of the above and wait for Brad.