Am I able to access a field added in a workflow (prefixed "custworkflow") in a workflow action script. I'm specifically trying to, and failing, in a beforeLoad in a WFA script. 🤔 (I have been referencing the field using newRecord and getValue using the internal id )

Can't say I've done it, but SuiteAnswers 79755 seems to indicate it's possible. That being said, even just for basic workflow UI stuff I've always had terrible results with workflow fields to the point where I've given up on them entirely and now just create normal transaction/entity/etc. custom fields that are hidden/disabled in all the places they shouldn't be in the UI.

You can try adding script parameters and passing the workflows fields as parameters on the action

Thanks for the replies chaps, I didn't get to the bottom of this in the end. The consultant creating the WF took a different approach. (sorry not privy to what that might have been!)