Improvements useful for potential event app

I am currently developing an app for festivals based on MusicBrainz data. Because of this i will add lots of events in Germany/Europe. But i think there are some changes to be done to the server to avoid unnecessary requests. Area chain search and Event Result Containing all sub Events (Comment, 4))
Event Art Archive will also be very nice.

If you’re working on an app, I imagine you’re more interested in improvements in the search API than in improvements to the search UI. While there is (probably) some overlap in the code, it might be a good idea to make it clear in your ticket which one you are interested in.

You didn’t say what kind of app you are creating. If it’s a web app (as opposed to a mobile app), you might want to look into having a SQL database on the webserver (or another computer in the same room), and replicating some/all of the Musicbrainz database into it. Then you can write SQL join queries to get what you want. That may be quicker than waiting for the Musicbrainz devs to implement the updates you’re asking for in your ticket.
I suspect that–unless someone has already been working on it for a while–the change you’re asking for won’t be done/released before next year.