I'm on the newest version of OSX, 10.9.3 (Mavericks). I downloaded B30 along with some workshop mods. I tried to start the game and got this error:

I thought it would be a mistype in "Thompson.ini", but it was typed correctly. I checked to see if the file exists, and it does. I tried commenting out the include line for "thompson.ini" in Ronin.rte/devices/devices.ini, but the game gave me the same error message. I think it might be a mod causing problems, so I'll try disabling them one by one.

That is most likely a mod and also the problem might be because they use \ instead of /
You can try doing a search and replace in the filesystem for files that contain \ and replace every instance with / to fix it.