Yes, the Wikipedia pages are definitely odd, and also inaccurate. As I understand it the last three steam locos on the Keeler branch were indeed no's. 8, 9 and 18 but no's. 8 and 18 were both retired in the mid-1950's when diesel no. 1 arrived and it was only no. 9 which was retained as a spare loco between then and when the line closed in 1960. No. 8 is now in a park at Sparks NV and is clearly visible on Google Maps. No. 9 is at the Laws museum and no doubt there will be opportunities to photograph no. 18 alongside it. It looks like an excellent event and it should be well worth travelling a long distance to attend it.
James