I'm sorry for my too late response.
When I created own test plan, I don't use the "JMeter test plan generator" plugin.
I only used the JMeter.
The JMeter proxy can record HTTP queries.
At first, I went to my Moodle site via the JMeter proxy and did a series of operations for quiz.
Operations includes "login", "visit course", "visit quiz page", "start quiz", "send answer", "view review page", "move to course", and "logout".
Then, a JMX file was created.
Second, I removed unnecessary HTTP queries from test plan.
The JMeter do not render web page.
URLs for cached
CSS and
JavaScript files about "theme" are temporary, these URLs may not be available at a later date.
So, I removed these URLs from test plan.
Then, at each HTTP query, I replaced server name, Moodle root path, and values of parameters with variable names.
For quiz queries, attempt ID is used in parameter item names.
So, I used parameter item names include attempt ID and question number.
After that, I added a mechanism to set initial parameters, get command line parameters, and get session ID and attempt ID from the source of the web page (response content).
These tasks were complicated.
This procedure is very long, and complicated, and my english is poor.
So, it's hard for me to explain these details.
Regards,