Thank you for reporting this bug.
In terms of post count, it feels correct. To display this number, we are using data from the /reviewable/334.json request. Data from /admin/users/29.json request is only used for IP lookup.
The difference between those two requests is that the first one is using User.user_stat.post_count, which counts only public posts (excluding posts in private categories and PMs). The second - admin - request is returning all the posts (including those in private categories and PMs).
In my case, 32 is displayed, even if the admin’s post count is 36.
Is it possible that your users have 5 private messages or posts in restricted categories?
I am still investigating the incorrect joined date. Does refreshing the page help?