We eventually had to create a replica of Production specifically for such nonsense.
Well then we moved a lot more business logic that they "helped develop" that ran on a distributed platform closer to "real time" for the application, because it was very dynamic in nature, and couldn't be denormalized back into the DB and remain performant. So I had to build a new system for some of their ad hoc queries and teach them how to use it.
What eventually chuffed me was realizing the "R&D" person I was "training" on the system always wore a different three piece suit every day and at least in fashion signals was probably making a magnitude higher salary than me for slower, wronger answers than any system I worked on, but probably was great at throwing it (very slowly) into very fancy graphs in Excel and useless salesmanship.
There were a lot of reasons I already wasn't long for that job at that point, but that was a lasting lesson that quality and performance won't matter to certain styles of upper management.
The non-engineers also decided to write their own internal tool, with no review and zero attention to quality. It’s been outputting wrong results that will cost them a few million at least.