OP here (hi!). I have awarded the green checkmark to @MOehm's answer for being the most complete (the LITS solved state is presented, the hidden connecting wall is identified, and the final one-word answer has been found). I also highly commend the answer by @Sconibulus for verbalising a logical path through the LITS grid deduction process and being first to ...
Partial answer, stuck near the last step.
Diagram (apologies for messiness):
Pulling the words out, we get these lists:
These look a little like they might be Connect Walls... and I've maybe got these categories?
Partial answer for the LITS, I believed I have encountered an error.
The big aha moment (putting it early to not waste time):
Some more logic:
A very nice little step here:
And now I think I have reached a contradiction.
And this is the problem:
For the other genre:
EDIT: I would fix this today, but it's getting late where I'm from, so ...