that’s odd! As long as the cars are in the same directory the title cart should load the game cart correctly. No experience of the trimui brick I’m afraid. Is it running a real Pico-8 installation or emulated?
I'm having the same problem when trying to play the game natively through Pico-8 on PC, I run the title cart, change settings, choose 18 or 9 holes and the cart just loops every time I press 18 or 9 holes!
Same if I try to quit through the end screen 19th hole option!
EDIT for addition.
Just tried it out on my Powkiddy RGB30 natively via Pico-8 through Rocknix and it works faultlessly. NICE.