Update #3 which was just posted is from around a week ago, but for some reason didn't actually get posted. Sad face. Sorry.
The server is now processing the last 52 weeks of data for all countries, it's about 27 weeks in and will be finished in about a day, maybe two. There are six countries which still have bugs, they're all tiny, geographically speaking. Tuvalu, the Maldives. Places like that. There's a problem processing very small islands that I'm working on.
The code is now openly available too, on GitLab here: https://gitlab.com/CoastHeavyIndustries/OSM-stats and here: https://gitlab.com/CoastHeavyIndustries/OSM-stats-frontend