OK. So you are a Belgian citizen, living in Spain and married since 5 years to a Dominican lady living in the DR. Right?
As a EU citizen, yo can live in any of the EU countries, either without a Spanish Residencia or after having applied for a permanent Residencia. Obviously, you primary residence apparently being in Spain, you tried to apply for her immigration at the Spanish consulate in the DR(?).
I was you, I would apply at the Belgian consulate. You ARE Belgian, and whether you live in a different EU country (of which you are NOT a citizen?), you sill have rights to be served by your Belgian consulate. I think that you would have much better chances there.
The Spanish consular agencies have a history of snobbing applications from foreign residents of their country.
Once you have a spousal visa for her to come to Belgium, she should be able to travel throughout the whole of the EU.
Another way, would seem for her to apply for a treaty WORD visa. Spain and the DR have several by lateral treaties. One allows for Dominicans to be RECRUITED for work in Spain. You would need a FORMAL working contract offer from an employer in Spain.
Just some general thoughts... J-D.