No, that is all you need to do. Connect the Shield pins to the equivalent "official Teensy pins". Just as if you had the Teensy mounted in the Sparkfun Adapter with shield mating the Arduino headers.
I do not actually have the Sparkfun adapter. Just Arduino headers on protoboard.
It is always wise to run the LCD_ID_readreg sketch with your newly wired shield.
This will confirm that everything is wired correctly.
My ST7789 controller seems to be very fussy about the speed. It is not happy with the minimum cycle timing from the datasheet. (most other controllers will often work faster than spec)
If you get glitches, please tell me. I can show you how to slow it down.
David.