After making some improvements and posting to MeFi projects, there were just 72 people playing fastr at the same time. Surprisingly enough, it's still working. The first website I saw pointing to it was Tecnicalia, a Spanish tech blog. That made me think maybe it was worthwhile making a Spanish version. I thought it would be a fun way to practice a second language, and also let Spanish speakers play in their first language. But I haven't seen anyone playing it yet.
If you want to improve it, I (a Spanish native) would use just "Nombre:" o "Nombre de usuario" instead of "Inscribe"; "Puntuaciones" instead of "Puntuaciónes", and "Acerca de" instead of "sobre", as it is its usual translation.
Keep up the good work! ¡Muchas gracias otra vez!