Hi,
I'm a mac user and came across Therian Saga by chance but encountered the same problems. Unfortunately Firefox is my main browser and handling two versions with the Firefox Profile manager is a pain in ... ;D
So using the 52.09 version of Firefox wasn't a solution for me. But since this all ist to the silverlight problem there is an easy way: iCab. It's a browser that is actively developed, free to use (but you should think of supporting the developer and pay the shareware) and still supports Silverlight.
So this is my solution for the moment, but I hope for a working wine Port to run the client or even better for a native Mac OS client (Its alway good to have dreams
).
Have a nice start into the new year.
PS: I lamost forgot the link:
http://www.icab.de/