I'm not any kind of professional! This is just from my own reading around and
may be wrong. I think the L'+F-K is a way of validating the answers. Depending on the numbers that L, F and K represent, that gives some indication of whether you are under or over reporting symptoms. And of how you feel about those issues. It isn't a diagnosis in itself.
Legal rights to the raw score data are likely to vary by country and state. If there's a Citizens Advice Bureau near you. Or similar. Or a Mental Health Support Line. They would be the best people to contact about that. Because they'll be familiar with the relevant law.
I would add that knowing the raw scores might not be useful to you. As I understand it, dozens of individual scores overlap. And combine in different ways. To suggest different diagnoses. They don't, again as I understand it, say "You Have X."
Edited to add- there's some more information about the Welch code here. This also shows why I don't think raw data would be very useful.
http://www.neurographica.org/welch.html L' I think means a score of 70 – 79 for L. And -K could be 60-69. But I have no idea about anything else.