Ok, I am not familiar with Google Input Tools - but my suggestion would be to first disable these and use instead the default input method provided by your operating system. MacOS and Windows both provide a Cantonese (Traditional) input method. if these works fine (as they do for me), then the issue is probably with the Google Input Tools and not with Coda.
for reference: I am using the standard pinyin keyboard on Mac Os and run coda in Chrome, and I have no issues.