Hi, looks like we were the only two who managed to keep Selenium IDE going until the 2.9.1 addon disappeared.
I tried the latest Selenium IDE but it couldn't handle my scripts and kept hitting an e undefined error when trying to import the files which I had to rename from html to htm.
Not sure how far you got, but I started moving to Katalon Recorder (free for Chrome + Firefox). It takes Selenium IDE files and also takes the user-extension files, but doesn't seem to read the global variables from the globals extension. So looking to create a globals file for each test suite. Meaning it's more like a local variables file.
They also have Katalon Studio which apparently handles globals better, but may be a step up from the simplicities of our HTML files.
cheers
Phil