What a shit, I'm sorry to hear that. I'm afraid of that, too, I always hope they are only on the lookout for smaller valuables instead of big instruments, but if they have enough time, you can't be sure.
You seem to live too close to Northrhine-Westphalia... As you probably know, we are experiencing record burglary numbers here, mostly due to organized burglar networks from abroad who disappear to their home countries again due to the open borders within Europe... terrible problem.
And what a pain if it is about things like musical instruments you put a lot of emotions in.