It seems that it is not possible to reference custom components from inside a custom widget. The reason why is eluding me.
I'm curious to know if there been any statements from the FF team on this.
It's surely a requested feature during 2024 as seen in the below results from a quick google search:
https://github.com/FlutterFlow/flutterflow-issues/issues/2763
Suggested workarounds:
1) import the path and check "Exclude from compilation".
This prevents the Test feature from working so now the project can't run in the browser which is a big part of why FF is awesome. Sacrificing this is not acceptable.