Doesn't seem to be any relevant changes in the repo between v3.10.2 and v3.10.3, and the theme hasn't changed. Obviously the HTMLHelp tools haven't changed in a decade or so, and the only difference in the build logs looks like less errors in the later one (apparently index terms didn't get fixed up properly in 3.10.2).

So other than running the build again and hoping (which we'll likely be doing later this week anyway), doesn't seem to be anything that can be fixed here.