When an alternate name format is used in a template, if it doesn't exist on the constituent record, then the primary salutation of a constituent is used as the fall back for BOTH the addressee and salutation.

It makes more sense to use the corresponding format for this purpose. For example "addressee" should be used as the default fallback for alternate addressee format, while the "salutation" should be used as the default fallback for alternate salutation format.