Ok so about the first issue my hunch was accurate: in first versions of the Offline Compenium, a trailing comma remained in all dataX.js files.
Since this is not valid JSON syntax he must have had changed it in following versions since this can cause crash on some browsers.
Now about that 'bs4', the last generated versions of exe files should come with it bundled.
I even tested it on a friend's computer (Windows 10, without any development environment inside) just this morning and it worked well. So I don't get why it won't for you :(
Would you mind re-download the whole project zip and retry launching the exe file, first without and then with the dataX.js files in the source folder?