page is not loading for french language

I'd give a closer look at SEF and sh404 settings.

This is an old issue we have facing from beginning.

we have asked the falang and sh404sef. they said this is the issue the CP extension.

I can say that's not a Falang issue nor a Custom Properties issue nor a standard Joomla SEF issue, because our demo site (solidsystem.it/demo31) works just fine and because your site on our server without sh404 works fine as well.
As I said we're unable to test sh404 on our server because we have no licence.
Also it's not our duty to debug someone else's site / extension.

If you want us to debug your installation we need FTP access, admin credentials and a contract.

Thank You for your support. We have mailed you the admin access and ftp.

Could you look into the issue.

Thanks to you. We look into this matter right away.