Hi,
I´m sorry that I don´t have a solution for this issue. However, as an alternative maybe this rough solution would fit better:
1. Create a UI5 library
2. Create a custom control within this library (your toolbar)
3. Import the library via bootsrap in index.html or via sap.ui.getCore().loadLibary()
Maybe the following thread is interesting for you: https://scn.sap.com/thread/3502503
This way you shouldn´t have problems to handle events as it is like normal event handling for other controls.
Best regards,
Sebastian