Include Parsley and get it to either show input errors or go to processlogon.asp
Only allow logon from staff if they are on a desktop, if they are on a mobile tell them only Translators can log on with mobile devices

Have a hidden field on the form devicetype and populate this using jquery, then when in processlogon.asp pick up this form value and set session variable session("devicetype") to either "mobile" or "desktop"