In the last release of October there is a useful new property for the repeater. Into the fields.yaml you can use a new tag to keep the items collapsed by default:

style: collapsed

This just works, but if someone edit the form via the Builder plugin, this new field is missed and every time we should re-add via code editor

The same problem with 'titleFrom'.

Well, it's clear that the fields not editable via Builder are missed after an edit + save, even if we added previously editing directly the fields.yaml

@guglielmana34864 Thanks for the report - I will add that in to the Builder plugin in the next day or so and push out a new version to support that property.

Thank you so much Benno, will be really useful because are two properties I'm using a lot in this new project.