The VisualEditor explicitly sets all images that are inserted using the dialog as thumb and right. "thumb" is fine, because it's not default, but that's what people want most of the time, but "right" shouldn't be there. "right" is the default for left-to-right Wikipedias, so it's redundant in English. The default for right-to-left Wikipedias is "left", so for these languages this behavior is unexpected.
The best solution is simply not to set the alignment and let the user change if it is needed.