I agree with you on the amount of space available on the Jupiter theme (but that's another theme that hasn't gotten anything to do with WHM, though). It can't be fixed pretty easily by removing the "container-lg" class on the div for the main content.
The "Site Monitor" error is also related to cPanel and not WHM (and not even theme related). We also get that error. AFAIK, it's not available in Stable yet, so hopefully it's fixed by then.
Now, the only issue you seem to be reporting that's actually about the new WHM theme is the search function (unless I misunderstand what you're trying to say), and that has already been mentioned multiple times. I'm sure that will get fixed as well.
The "Site Monitor" error is also related to cPanel and not WHM (and not even theme related). We also get that error. AFAIK, it's not available in Stable yet, so hopefully it's fixed by then.
Now, the only issue you seem to be reporting that's actually about the new WHM theme is the search function (unless I misunderstand what you're trying to say), and that has already been mentioned multiple times. I'm sure that will get fixed as well.