How to replace the standard message
You work on the CRM WebUI, and a standard message is displayed after you perform an action, but the message text does not meet your requirement, and you want to replace the existing standard message with your own message.
CRM has the functionality that you can replace the existing message with your own messages that are created in your namespace. You can replace the existing message text with your own message text. The customizing path is:
SPRO -> Customer Relationship Management -> UI Framework -> UI Framework Definition -> Define Messages to Be Replaced
If this cann’t fullfill your requirement, you may try BADI WCF_ALTER_UI_MESSAGES.