Hey Mr. Crayfish, In the "en_US.lang" file in the assets<vehicle<lang folder of the file, I found that the name for the Dirt Bike is ever so slightly off. I fixed it, simply by setting line 103 to "entity.vehicle.dirt_bike.name=Dirt Bike" (without quotation marks). You can fix this yourself, or I can give you the fixed jar file and you can simply upload that to your website and Curseforge and everywhere the file is. Link to fixed file

While I may be an en_uk person it is still good to know that stuff is fixed.