It might be worth your while to look into the ConsoleTools Lua Framework that I have recently published. One of its goals is to make development of Lua scripts for Dorico more straightforward, and the documentation’s appendix C provides a walkthrough of two example Dorico Lua scripts that are included with the framework.
Caveat: the current main restriction of Dorico’s scripting capabilities – the inability to retrieve useful contextual information from the Dorico application – is something that ConsoleTools cannot compensate.