Yes, it's quite annoying, but at least it has made me think about the next steps on how I want to progress with these flight plans going forward.
Although the operator's address is normally listed, I don't use the information as I rely on tracking data only. A long time ago, when I used my own version of the RPP spreadsheet (or it could have been even before that), I used geolocation of US post codes to find the nearest airport for all US registered aircraft.
This works for most countries I think. In France the base airport is listed in the registry itself, which is very helpful.
The issue is for countries where this information isn't freely available, such as privately owned aircraft in Sweden.