Windows – Group Policy: Autohide or disable task bar

This is a User config, you needed to have this apply to your environment based on the computer, not the user, so you'll need to set the Group Policy loopback processing. That is found under:

Computer Configuration > Administrative Templates > System > Group Policy > User Group Policy Loopback Processing Mode 

To set the policy for language and regional settings. In the console tree under User Configuration > Preferences > Control Panel Settings. Right-click the Regional Options > New > Regional Options

http://technet.microsoft.com/en-us/library/cc754020.aspx

To answer your second question about enforcing. I would create an OU for your Kiosk workstations. Under that I would create an OU for each Region. I would put each of your workstations in the specific region container. That way you can apply group policy settings to your Kiosk OU and it will apply to the Region OU as well. Then you can manage each of the regional options inside your Region OU

Kiosk
   |-Italy
   |-Russia
   |-Spain
   |-USA

It likely has to do with you using folder redirect without offline files of crucial folders like ~Desktop, and setting those via manual reg rather then the "supported" way of Group Policy folder redirect. Disabling offline files for crucial folders will affect performance as each computer constantly has to send SMB packets back and forth since those shared folders are "online only". This is not Microsoft best practice. Three things I would do that would likely resolve your issue, put you back in the realm of "common use and MS supported", likely improve desktop Windows Explorer performance, and reduce network traffic.

• Enable offline files, they "just work" in Windows 7. Any redirected folder will auto sync for offline use.
• Use Group Policy "folder redirection" to control user folders, rather then setting registry settings via GPP.
• Rather then the "old school" way of pointing people to a shared network folder for shortcuts, I would use GPP shortcuts feature to create those locally. Also, no need to use common desktop redirection if you're using GPP user shortcuts (it just creates the tiny .lnk files in each users local profile). I've used this for hundreds of shortcuts (pointing to local and network files) on networks with over 4,000 computers (even in XP) with no issues. If there was ever an issue it was permissions related and GPP would state it clearly in Event Logs.

Basically, IMO, your using GPP wrong. Using GPP to set reg settings when there are other more-supported ways in Group Policy to do it is just asking for trouble :)