Hi back!
I'm happy to see someone else using NRaas Traveler. I've been using it in my TJ game for almost 2 years now, and will soon be moving to my 11th town.
I don't use a mac but I'm sure the steps are similar.
One thing I wanted to mention is that visitors to towns aren't actually the full version of your sim from the original town, just mini versions.
And adding those versions to your town isn't recommended, from what I understand.
Though I do believe you could use NRaas Master Controller to add the full versions from your original town, if your customized version of Appaloosa Plains lists them as residents.
I had similar issues with using the EA world Adventureland and it didn't actually let me do that since Adventureland has the same identifying number as Sunset Valley.
If I had let Igazor know my original town was Adventureland, then I could have saved myself a lot of work.
But my traveling sims had a great time is Starlight Shores, even if the sims I added from Adventureland using Master Controller>add sim didn't actually move due the conflict with my town and Sunset Valley.
Have you posted your issue with Traveler on the Nraas site, mentioning you are using a mac and a customized Appaloosa Plains?
Igazor or another member of the site may be able to provide the reason it's not working for you.
Better yet, they might be able to help you get it to work.
Admin and members at the NRaas site have been very helpful and patient with all of my questions about Sims 3 and NRaas mods.
Between them and the helpful admin and members on this Forum, it's really made my Sims 3 experience a much more positive one.