I tried to upload Czech and Frech and I have the same problems, they doesn't work becouse I read time out message but they were uploaded but in wrong manner becouse in the storefront and also in backend when you switch language you could read LocaleResource Name Value instead of the correspondent Value for example
you found "Account.AccountActivation" instead of "Aktivace účtu"
I think it is the same for Spanish and probably it is a bug.
