With mendix pre 3 we have some fusion charts that work perfectly fine in the cloud. I would expect them to work in the 3+ versions as well.
I can confirm that it works in the cloud. However in the version of the widget that I use the HTML code used lowercase characters for the JS file where the file itself has mixed-case. That does not work in the cloud because that seems to be based on Linux. Make sure that filenames and references to filenames are consistent.