Is dyslexia unheard of in Spain?
It's heard of, as dyslexia has much broader meaning than just phonetic problems. There is for example FEDIS (Spanish Dyslexia Federation), which advocates for special treatment of children with dyslexia in Spanish education system.
However, there is grain of truth in this. Indeed Spanish children affected by dyslexia have much less problems reading and properly pronouncing words, than English speaking children.
It has been demonstrated in this study: "Valoración del procesamiento ortográfico en niños españoles con dislexia: El papel de las unidades léxicas y subléxicas" (roughly translated title: "Evaluation of orthographic processing of Spanish children with dyslexia: The role of lexical and sublexical units").
Part of the conclusions:
Los resultados de la presente
investigación tienen implicaciones en
la práctica educativa. Sugieren que
mientras que es necesario entrenar en
la estrategia léxica a los niños con
dislexia, ya que muestran un déficit
en esta habilidad de procesamiento, no
parece indicado entrenarles en
habilidades morfológicas, ya que, en
un sistema ortográfico transparente
como el español, el morfema no es
imprescindible para acceder al léxico.
(translation):
Results of current investigation have implication in education practice.
They suggest, that while it is necessary to train children with dyslexia
in lexical strategy, given that they do have difficulties with processing
abilities, it doesn't seem appropriate
train their morphological abilities, as in spelling system as transparent as Spanish,
morpheme is not indispensable to access the lexicon.
And the part that directly compares Spanish to English:
Sin embargo, algunas ortografías,
distintas al español, no son
enteramente predecibles sobre las
bases de los fonemas ya que no son
sistemas transparentes. Esto es así
para la notoriamente lengua
“irregular”, como el inglés y, por
extensión, el danés y el francés.
Estas lenguas están gobernadas, no
sólo por la fonología sino también
por la morfología.
(translation):
However, some spelling systems,
other than Spanish, are not
entirely predictable on
basis of phonemes as they are not
transparent systems. This is
the case of notoriously
"irregular" language as the English, and
by extension, also Danish and French.
These languages are governed, not
only by phonology but also
by morphology.
BTW. Spanish (and few other languages) are pronounced as they are spelled, but that doesn't work other way around. There are many homophones in Spanish.