You can create copies of the e-mail templates for the different locales, using the Java locale-naming convention: to create localized versions of (say) operations_sendEmailWithLicenseAttachmentTemplate.xsl, make a copy and name it ...Template_fr.xsl for French, ...Template_es.xsl for Spanish, and so forth, and then rebuild the site with flexnet site make.
Searching the FLEXnet Operations Implementation Guide for "locale" will give more details.
When the FNO server will use the "localized" version of the template? I would expect that this is happening if the contact person have that "locale"? Or is ti when the FNO web user have that locale?
It depends how you're sending the e-mail, but the pages from which you can e-mail licenses, entitlement certificates, etc., should show a language-selection list once you've set things up:
