The default Share workflow form UI does not support Aikau - not natively and not via the (suspended) development effort you read about. You are correct in your understanding that the forms engine work was focussed on transforming the existing XML configuration into a usable Aikau form. This feature was meant to be used within Aikau components / pages.
Your clarity is very valuable and much appreciated.
I understand how to make a custom FTL based template which I can include in an XML form definition. I dont understand how to make a complete custom form - are there any blogs/documentation you are aware of. Once again thanks for your time.
If you were to create a custom form based on Aikau you wouldn't really have to bother with FTL and XML form definition anymore. Take a look at the AIkau examples / tutorials that exist, e.g. Aikau Mini-Examples - Simple Form or Tutorial Chapter 7 and 16.
Oh - so the actual question then is how you can extend the default Share UI for workflows to show Aikau forms. That was not apparent to me from the beginning. Well, that is actually the tricky part because the legacy YUI 2 UI for workflows in Alfresco Share is one of the most annoyingly fidgety things to customise - no one had ever put any effort into making that easily customisable.
You might want to consider to add make a customisation to the "Alfresco.component.TaskList" widget (found in task-list.js which is part of the "My Tasks" page) and its function "renderCellActions" which will render the page links for task details / edit forms. You could - for specific types of tasks - substitute the link with an URL to your Aikau-based task form page.