what do you mean change a template? Lets make sure we are talking the same thing
Here is the customer service template IslandAquatics.com - Reeftalk Reviews
Here is a regular product template CS8 Series - Reeftalk Reviews
Now if I go in and change a regular category to customer service I see the resulting product fine CS8 Series - Reeftalk Reviews
So I guess lets try and clarify what you mean here as I know you have recently modified things lately. Maybe yours is as simple as you have not created all the new needed language files since you created a new language recently? Remember the template addition system still requires a directory under the languages directory with certain scriptnames to override default language strings.