My spanish fluency is 3% and I conquered the spanish tree, level 11, what's that about?
My french fluency is 11% and I can't barely eve say hello :P
Your Spanish tree is probably not in a golden state and most of the words are in a weak state. Based on the word strength, it's estimating a low fluency. For the French, you probably have just started and the skills are golden (good word strength). But the number of words learnt is still low. Hence it shows a better fluency percentage, but still not very high.
I have just noticed the Fluency Shield! Kind of weird... It used to indicate in another place a higher percentage. Do anyone know how this percentage is calculated? I finished my tree long ago, and continue Duolingo on a daily basis but it only shows at 55%! (the shield is on the top right corner of your home screen in a yellow colour -can not speak for the mobile version)