It's iWeb web publishing software.
I saw on a compatibility list that iWeb won't work on anything newer than Sierra. I haven't tested this yet, but I will. My website is built with iWeb, and until I get around to converting the site to something else, I'll still need to run iWeb. Since it's not something that I use very frequently, it's no problem running it from an external drive.
I tried to find that compatibility site again just now, but I couldn't find it. It's been a couple of years since I saw it. It listed all of the most popular Mac software and all of the versions of MacOS that they were compatible with.
BTW, the flickering problem didn't go away. One of the suggestions had been to uncheck the "Automatic graphics switching" option in the Energy Saver settings. Unfortunately, this option doesn't show up in my Energy Saver settings. The High Sierra version is the same as Sierra. So, they must have added that option in a later OS version. The flickering isn't excessive so far. I guess I'll have to live with it. And it seems to be okay with an external monitor. So I may use it that way until the computer dies completely. It's nearly six years old now. I don't think I can expect much more from it, considering how they build them these days. I guess it's time to start looking for a replacement.
