Hi Luca,
(1) The RailClone plug-in is primarily designed to handle geometry objects, so a preview like the one showing these cones is not supported. This would require instancing these segments using the RailClone Tools utility.
(2) Instead of using a Fixed Size for spacing the lights in the Default Input, the Evenly Input would be a better fit for this scenario. Please find the revised version of your scene attached (241113_TaxiwayExample_ITOOSOFT.max).
I hope this helps.
Best regards,