Not sure though were you would be seeing this message event then though. Could you elaborate?
The event name is timer event and is attached to the sub process.
I don't understand why to use message event as timer and not timer event with atttachedTo property to sub process
I just found in the documentation that there is a boundary event that looks like a regular message that and I have to add manually
<boundaryEvent id="_4" name="TimerEvent" attachedToRef="_2" cancelActivity="false" >