I tried to check as much as possible. Chimay is another one that was a nasty one... but I had the correct one. Doing a strong effort (I think I visited over 90% of the found sites)

I indeed wasn't aware of that, did look into it... created a wiki page but by the time it was ready to save, I got logged out again... I'm working on it.

Created a page here:
osm.wiki/Mechanical_Edits/european_city_websites

... and will not have the script run automatically until (1) someone looked into it... and (2) I successfully updated 1 or 2 cities in a step by step mode running the script.

Anyways, given I'm trying to collect this list for multiple countries in Europe, I thought it would make sense to also submit these to OSM, as they are a valuable resource to the municipality object.

Basically, what I have done, is auto-generate potential domains that could be valid city domains (for Belgium testing where cityname.be was valid, and if not... just search by hand what was the official cities website). So the source is the website itself. (e.g. vilvoorde.be or izegem.be)

The hard part, was to establish what node can be considered the municipality.

Argh! My very sincere apologies!
I thought my script only checked if a municipality had a website - and if it didn't have one, it added it. It wasn't meant to remove any data (except for websites that returned a 50x response) when I had a better alternative.
Please feel free to revert my work. I'll see to separate out the script that looked up (and validates) websites and submitted the missing ones.
Not sure how to interpret the deep history link. But since this is my first dive into the OSM API, I'm confident I messed up.

Yes, that was indeed very painful. My apologies. I try to separate them individually.