This mod currently works on 4.1.12 and it was developed on 3.5.x
https://vborg.vbsupport.ru/showthrea...ighlight=style
I think the issue with any user->style counter is that when a user uses the actual style chooser in the footer, they are not actually setting it as their style its a temporary choice and will not be counted, but when a user sets their style manually in their user settings (usercp.php) those will be counted correctly.
The mod listed will show how many users are using what style (only for users that have set their style) in the style chooser.