The application data is user-specific even though the app itself is system wide as you noted.
So you didn't mention, but I assume you did try running it there it there in the new user account? And I assume you did double-check to make sure LibreOffice's advanced settings showed the 1.8 JDK?

So to clarify, what my screen shows are both JDK versions (not JRE). LibreOffice will only work on 1.8 Java (at least based on my testing). If I switch to 1.11 Java I get the same error you do. Finally, switching Java requires you close and re-launch LibreOffice. I can usually switch once, but if I switch again it will crash.
That being said, here is my suggestion:
If you can't get this working based on the above information you go ahead and install the 1.11 JDK as well so you can actually have something to switch to....and go ahead switch to that, then close LibreOffice. For me it doesn't work with 1.11, you can try it but I assume you will get the same error. Then re-open LibreOffice, verify it shows 1.11 still as active, then switch back to Java 1.8. Then, Apply and Close that. Close LibreOffice, don't test the database functions yet. Then, re-open LibreOffice and test it out making sure it still shows 1.8. And be sure you are doing this using the test user account.
To explain, my long-shot theory (if nothing else) is that have two Java's installed so that you can have one to switch to temporarily then switch back to 1.8, may actually help make sure LibreOffice is really using what is selected (as opposed to their being only one option to select.
If this doesn't work, on the Advanced page you can click Expert and do a search for Java. This is what mine shows:

Not sure if this will help, but if none of this gets you on track you can post your own two screenshots of the same as I did above and we can see if anything jumps out.
Also note, in my case I have a bit older build of 1.8 (build 191) and not the latest 1.8 (build 271). I can't see this being the issue, but... if you want to try the exact same build that I'm using (191) you can get it through the archive page here: https://www.oracle.com/java/technologies/javase/javase8-archive-downloads.html
I'm also wondering if it's working for @Loner T (or anyone else) or not.