Java does not support Mac aliases at all. The only way to do this would be:
1. Write a bunch of Mac-specific native code
2. Write a bridge interface for the native code in Java
3. Identify every single point where we resolve paths in OmegaT and replace the current code with a wrapper that will use the native bridge when appropriate

Basically this is never going to happen, and frankly I think spending any effort on this doesn't make sense given OmegaT's mission to be a cross-platform tool.