It happens the same with "imagen", which could also refer to a pictorical representation -which seems not to be the case here.
As for your interesting comment in answers, there is no reason to suspect a personal involvement of Alfonso X here -as there is with the Alphonsine tables.
The original context states "Ejemplar dedicado a: X SEMANA DE ESTUDIOS ALFONSÍES : Religión y sociedad en tiempos de Alfonso X : culto y devoción marianos".
And the text does not include any note relating these images to Alfonso X other than the acceptance of the reasonable possibility that those images correspond to the times of Alfonso's occupation of the rural area of Jerez and particularly Alcanate.
https://www.google.es/url?sa=t&source=web&rct=j&url=http://i...Of course, there is also a mythical historiography -but I don't think it is so relevant here.
Anyhow, this being said, I don't see no problem with your proposed translation as Alfonsine images of the Virgin Mary, which relates to the original with just the same degree of understandable ambiguity.