Hi gmar5, cheers for the comment and link. I've taken a look, and also looked at your update to the building. Very helpful, thank you. I should be able to future similar issues :)

As mentioned in the changeset text, I've been updating WI halls to add in the wikidata reference (to hopefully help future users find all such halls).

This particular one has previously been mapped in detail to show the roof shape etc. I added the brand:wikidata tag into the relation, however JOSM advises that the relation has errors.

I searched the internet to find the error, but couldn't work out the fix. I'd be grateful if someone could fix it (and explain what needs to be done so that I can fix future similar issues should I find them) - Cheers!

These changes were made using the StreetComplete app, so there was no control over any relation modification.

The app just asks questions and updates based on the answers. From the looks of it, it asked the smoothness of the route and I noted that it changed part way along. StreetComplete then split the path as noted.
Is this likely a StreetComplete bug where it's not adding the newly split way into the relation?

Hi,
This changeset updated the Berliner Fernsehturm to 3cm high. Is this intended?
osm.org/way/556435241