When I was in construction we put them In the controller, even remote machine rooms. It wasn't until I went to service that I saw LN cards in the hoistway. It looks like they did that in the beginning but I don't know when they decided they didn't have to. They are sure a lot easier to work on in the controller!
The pico fuses are only on the LN card, you should only have one. For troubleshooting purposes you can use a good L24 card from the car to try to get your SPI loop up. SPI loop problems can be a pain. You really need spare L24 cards and a good CAT5 tester to find cable/plug problems. But with SPI loop problems you usually have some lanterns and buttons lit and I think you said you had no faults so I'm thinking the pico for fixture power on the LN card.
