After performing a fresh Arduino environment install, then adding the Tsunami board and library as instructed, I ran into problems whenever I tried to upload (weather to the Tsunami or a normal Arduino board). I suspect some part of the Tsunami board/hardware definition doesn't quite work under OSX, but I need to spend more time to track it down.
Uninstalling the Tsunami board (from Board Manager) allowed everything to work again (I can even upload to the Tsunami by treating it like an Arduino Leonardo).
The error I get related to the upload via avrdude (and I'll need to recreate the problem to grab it in full, but this is from memory):
Cannot execute program '___REMOVE___/bin/avrdude': File or directory not found.
I've searched for '___REMOVE___' in the installed files but have not been able to determine where it comes from.
Hm. I just tried this on OSX (10.10.5) with the latest IDE, and I'm afraid I'm unable to reproduce it. With the Tsunami libraries and board files installed, I'm able to program both a Tsunami and an Arduino Uno.
If you are able to do any debugging and find further information, I'd be grateful. And if anyone else runs into this issue, please let me know here.
Just about to give up on this. For reference, here is the complete output from an upload (this is for the selftest example application):
Sketch uses 11,328 bytes (39%) of program storage space. Maximum is 28,672 bytes.
Global variables use 941 bytes of dynamic memory.
java.io.IOException: Cannot run program "REMOVE/bin/avrdude": error=2, No such file or directory
Caused by: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.forkAndExec(Native Method)
... 11 more
I get this error whenever I try and upload with the Tsunami board installed, even if targeted a different board. if I uninstall Tsunami I can upload to the board if I treat it as a Leonardo, but I'm guessing that there are pin differences or something as selftest then fails.
Also for reference, if I the re-install the Tsunami library it complains that a file already exists - I need to go into the Arduino app library folder and manually delete the old Tsunami package for it to proceed. The problem then returns however.
I did have ONE day where it all seemed to start working; but the next day (after changing NOTHING about my setup) it started failing again.
If no one can find a solution I'll have to abandon the Tsunami and try other approaches. A shame; I am 90% through a nice little curve tracer utility combining a python command line app and the Tsunami (just state your desired frequency range and step, samples to average, how long to allow signal to settle and it writes a CSV file with the results).
I really want to help getting this working for you, but I still haven't been able to reproduce the problem, and nobody else has reported it either. Is there any way you can try and reproduce it on a different computer? Failing that, can you install a second copy of Arduino in another location and try reproducing it there?
Sources like  seem to suggest this is not necessarily a Tsunami / package-related issue. Without claiming to understand the exact cause, the linked post seems to imply simply downloading the hourly build from arduino.cc instead of the stable release (or possibly going back to 1.6.5) might solve this... Good luck!
 - http://forum.sodaq.com/t/autonomo-w-arduino-ide-1-6-6/41