When i tried to delete history for items in template i get "green" report - History cleared. It's confused for users.
I recall when i began studying Zabbix i spend much time to understand why history in templated items (Inherited from template) is not cleared.

Of course i should delete history for the inherited items directly, but it is sometimes forgotten Just now i again faced with this situation.
So, i think this report can be improved. For example "red" report "Items in template [usually] has no data history" or similar.

Another way - remove a choice of "Clear history for selected" from dropdown actions when editing *template*. But it's not better decision. IMHO. hmm, but maybe vice versa - it's better. At your decision