radiostar2000,
you are a british citizen,
your wife is a japanese citizen, residing in japan, applying for a residence visa in spain.
you got married in italy.
you are going to reside in spain.
and the spanish consulate in japan is requiring your wife an original british marriage certificate.
where in italy did you get married, italian courts or british consulate?
why don’t you apply for a british residence for your wife instead?
there is a new law not requiring visas for non eu citizen family of eu citizen as long as they can show previously issued residence cards proving they are related.