Anchor GUIs always display Ender Pearl ignoring whatever is configured as fuels.

Accepted fuels shall be displayed as configured in railcraft.cfg:

S:passive.fuel= minecraft:ender_pearl=12, minecraft:coal#0=4
S:personal.fuel= minecraft:ender_pearl=12, minecraft:coal#0=4
S:world.fuel= minecraft:ender_pearl=12, minecraft:coal#0=4

Given there my be several configured fuel types and required quantities:
Item icons followed by name and quantity could timely rotate as with recipe guides from NEI.

https://github.com/CovertJaguar/Railcraft-Localization/blob/master/assets/railcraft/lang/en_US.lang#L285

Funny right?

If someone wants write the code to make that happen, they are more than welcome to do so.