I'm not familiar with Macs but I've done a bit of searching around and this is what I've found.
Anyhoo, even though 'tis not required to use GIMP or Photoshop to make these map files, 'tis required to make the heightmap in grayscale form. Another reason why y'er files may not be working is that ye sent the exported files to a "random folder". x'D Send those files to the terrains folder found in (FeralHeart<media<terrains).
Make sure you have the heightmap image saved in your map's folder, located in your Terrains folder. When typing it make sure you type in the exact name of the heightmap image including the .png format.
The reason you're probably crashing in Ficho and Zama is because they're very detailed maps, and your Mac may not be able to handle that, so it crashes. I heard that turning off your music can also reduce your chances of crashing, but I don't know if this is a proven fact.
I went to check, and I've already got my Music, GUI, and Effects at zero :/
I've made maps (on my pc, when I had one), so I'm like, 80% sure it's a fault in my Mac, just being unable to handle details. Which sucks, but eh, that's what I get for using a mac.
Edit: On my pc, I was able to put height maps in the terrains folder. I put the height map in the map's folder, like suggested, and it loaded! Thank you
