Artboards renamed when saving to CS4 or below
When saving an Illustrator CC2020 file down to version CS4 (which we have to do for client reasons), when it's reopened it has renamed the Artboards. So, in my example, the file has two artboards called "Artboard 1" and "Artboard 2" (we need to keep them named that way too for html coding reasons). If the document is saved as CC2020 or down to CS5, the artboards retain those names and all is well. If, however, we save down to CS4 or lower, when the file is reopened (I'm using CC2020) the Artboards are called "Artboard 43" and "Artboard 44". If the file is saved again to CS4 and reopened, they've become "Artboard 45" and "Artboard 46"... and so it continues.
I'm using the latest CC2020 version running on the latest Catalina macOS.
The core issue is that CS4 file format does not have support to remember the artboard names, we introduced the artboard and naming functionality in CS5. So, nothing can be done to resolve this issue.