You could try to find out, which files Garmin software uses to store data and copy them over. Regression testing is quite some effort, but might yield the exact patch(es) that broke the communication, with that information you could file a bug, and hopefully the regression would be corrected in future wine versions. That would probably be the best solution. But there might be a much simpler way. Did you try to install older wine versions? Depending on your Linux and package manager this should be quite easy. Even if regression testing is to hard for you, you still could file a bug, pointing out, which wine release broke your software.
