Excellent tutorial and nice that you shared this!
I hope this kind of work encourages experienced users/developers to contribute device specific bindings on top of the generic modbus binding, so it would reduce the burden for new users with similar devices. Similar to work tried here with sunspec inverters.
This was one of the main design drivers with the new binding, enable hopefully easy way to build device specific bindings.
Btw, installation guide for the binding with openHAB 2.3 is described here: Modbus addon not work at openhab2.3.0