We have recently experienced an influx of users on our forum for whom English is not their primary language, and this addon serves as a valuable middle ground for maintaining a forum that is open to individuals from all backgrounds and ethnicities.
Regarding the styling, why did you include Bootstrap when the flag icons are enabled? It interferes with the forum's appearance and appears to cause overlapping issues with icons and elements in certain areas.
For example, the checkboxes get transformed into iconic icons, causing them to disrupt any customizations. The RSS button displays two different icons at the bottom of the page. Clicking on the country change drop-down produces a strange hover effect where it looks like there's a button within a button, primarily due to the added focus on the button. This issue occurs on the default style, but I have purchased custom styles in the past that change the navigation and header link/button colors, and those seems to get overwritten by this addon. Is there a way to disable the link/button text color overwrite? Additionally, it makes the text bold in places where it shouldn't, such as the forum widgets. It would overall look better if you used something more native to XF to style the drop-down or simply created custom CSS for it instead of relying on Bootstrap. Just my two scents, otherwise, this addon serves its purpose, and I purchased it a few hours ago, and had some overall feedback to provide if you find any of it useful