You know when you try to spawn a train and it spawn high up in the air? When it did that most of the time it will bounce, derail, and become unusable.

On the other hand when you try to spawn another train, it clipped into the ground and become a makeshift bomb.

Apparently the reason for the second one is because of the Switch part. The vertical spawning position is aligning the switches with the ground, making train with switch for things inside buried halfway into the ground.

Although, with a part that automatically attach to the ground when spawned, we can exploit this to fix the first problem. By attaching the Switch into a Detacher (set activation to 8) and placing it below the wheel, it will spawn at a few centimeter above the ground and preventing it from bouncing and derailed.

Here is the train when it spawned:

Here is the link for the train in the picture:
DICAT-5
KL-1000 Spawnable

Hope it helps!