Thanks Jon. I have downloaded the MCX tool but not the latest 'latest development' version and not yet tried it yet as it was getting late when I downloaded it.
I will take your advice to first try a new 'test' project and maybe just add water airport, water runways and parking spots with no docks, jetties eg very simple. I don't think I need water taxipaths? just for (user controlled) flights. I think it might be easier just to recreate the project rather than try and modify the old one.
added later-
Firstly I have read parts of the document ADE 2020 ALPHA 18 NOTES V1.pdf especially about building the project.
I started a new project (wow I had forgotten a lot but picked it up very quickly) and simply created a (WATER) airport, runway and start points for the runway (no taxi paths). And then thought I should attempt to 'compile' it by selecting 'file>build project" (not sure if that is what I should be doing but couldn't see anything else to try).
After the process it displayed
I have found some compiler errors during 'build project' and fixed as many as I could however the next to be fixed is
invalid package name cax3-sechelt water airport it should be in form aaa-bbb-...-xxx I guess it doesn't like the spaces . I found in project properties the name I had entered for 'package name was
cax3-sechelt water airport so I changed it to
cax3-sechelt-water-airport but still the build error continues.
By the way when is 'export xml' required? I have done it already but would like to know the significance.