Can't change AP Actor name anymore?

On earlier versions of gancio, i could determine the first part of the AP Actor name eg @calendar@instance.tld @events@instance.tld @fedi@instance.tld

With the new (exciting) improvements ongoing to gancio's federation (as described here https://gancio.org/federation) that is now set to @relay@instance.tld by default

My earlier instances are still using whatever custom name I set, but in newer instances there does not appear to be a way to change that name. Is it perhaps undocumented but changable in config.json? I am also concerned about updates to my current instances breaking because of this, if the name is no longer meant to be customizable (although I think it should be customizable).

This might be a side-issue but I understand the current efforts in federation mostly emphasize federation between gancio instances (which is cool!), but I personally find a lot of value in gancio federating with other parts of the Fediverse (users following a calendar from Mastodon, Pleroma, all the various forks, etc) and I would like to advocate for features that improve that experience as well!