You're adding /%wpforo-profile-account%/ in HTML so you'll get the same with domain name. You browser can't do a magic and replace it to real link, this is HTML code this is not PHP function. I've already explaned above that the best way to do this is replacing your dropdown HTML to WordPress menu system. Register a new menu location in WordPress theme functions.php, then navigate in Dashboard to Appearance > Menus, create new menu and attach to custom registered menu location.
More info how to register custom menus in Wordpress:
Step 1: Create custom menu location - Register menu
Step 2: Create custom menu with wpForo shordcodes and attach to custom menu location:
Making this more difficult than it should be, just create an easy way for us to call a user's profile, shouldn't have to do all that for such a simple feature. For example Easy Digital Downloads links the profile to yourwebsite.com/profile/ and the current user is automatically found. Why not do yoursite.com/forum/profile/ or something similar.