You can change the name with the information you have already found.

I also think Revit has changed at some point and the fab part names are derived from the ITM name in the fabrication database now.  I can't find reference to it but I'm pretty sure I saw that in the release notes somewhere.

You need to open / load Fabrication CADMEP into Autocad and edit the parts from there.

You will be able to see services and parts.

Draw something and type FOLDERS.

It will open a panel showing parts.  Right click and rename one.

You would then need to get the newly named part into the service.

Not hard but quite a few steps.

Here is a piece of it:

https://knowledge.autodesk.com/support/fabrication-products/learn-explore/caas/CloudHelp/cloudhelp/E...