It's hard to reproduce this issue on my development machine. I suspect some codepage issues here. I made some changes to the weather provider wrapper, please test the output with latest build. If this doesn't work again, I suggest to use the properties #WorldWeather.TodayWindSpeed and #WorldWeather.TodayWindDirection instead of #WorldWeather.TodayWind. Regarding weather coding description you can use #WorldWeather.TodayIconDescription or #WorldWeather.ForecastDay<digit>IconDescription alternatively. Please see the included manual for more information.
... would it be possible to show "random" backdrops for specific weather conditions?
Is it possible to make this more configurable? E.g. have one folder with several rain images and the plugin chooses randomly one picture out of that folder while the condition shows rain.