Customize messages for items submitted

Hello Michel_,

no need to "hack" ;) You can change message and language strings by configuration. Per type. You have to use the build-in Joomla language Override feature. Just add your NEW language CONSTANTS and values to your current site language.
By default it uses the following J! CONSTANTS. The 1st is for new items, the 2nd for edited/saved items:

JLIB_APPLICATION_SUBMIT_SAVE_SUCCESS
JLIB_APPLICATION_SAVE_SUCCESS

You might change the prefix parameter to MYSECTION1 or MYTYPE1.
Then add the new CONSTANTS in language override manager e.g.:

MYTYPE1_SUBMIT_SAVE_SUCCESS
MYTYPE2_SUBMIT_SAVE_SUCCESS
MYTYPE3_SUBMIT_SAVE_SUCCESS
etc.

Messages

See YourType -> Submission Behaviour

Notifications & Events

See YourSection -> Properties (scroll down, last parameter)
This allows you to change the singular "item label" in notifications. i.e. instead of "item" you might want to use "product" or "entry" etc.

I I works fine.

Many thanks.