As @flypig said, I don’t think that notification for a background task is desirable.
What I suggest instead to get the information is to be able to look at the sync logs in a way that is synthetic and convenient for the user, thus in the UI. Another possible feedback, for calendar sync at least would be mark out-of-sync events and allow the sync to continue on errors.
All of this I’m actually working on:
@flypig also worked on the Google sync plugin to allow sync to continue on particular sync fqilures : https://git.sailfishos.org/mer-core/buteo-sync-plugins-social/commit/f9b5f8d74ddf74eb49ebbc02012126466c776204
What @flypig suggested as a feedback for logs is to centralize in a list, like the transfer list, every sync results. I’m very much in that direction myself also. Various of the above mentioned merge requests should allow this. Hopefully the open source parts which represent the core of the changes will go in the various projects in the coming versions. The integration into the UI may take a bit more time, but I can provide an ugly app doing the job as soon as the open sources pieces will be officially distributed.
Please, comment or give your opinion on this so the developement can be influenced and improved before being accepted.