Thank you. I edited my original post to mention that I’m not talking about bulk modifications to the database and things like that.
The forum in question is self hosted. It has been running for over 10 years. It’s maybe medium size? I don’t know all the details, but there are probably about 100-200 posts per day. Maybe 2-8 new threads each day. There is a quality moderation team made up of about 5 active mods.
As far as I know it does not have customization beyond (perhaps) a simple custom theme. There is one feature that turns abbreviated citations in posts to links using regex. We have had that for some time and it has never caused any problems that I know of.
The forum itself runs very well and there isn’t much complicated about it. In fact the admin’s strict and conservative approach to management is part of the problem. So I wouldn’t expect that there would be problems waiting for the next admin to have to deal with.