The operative law concerning indulgences is in the Enchiridion Indulgentiarum ("Handbook of Indulgences"). It says you have to have, minimally, 14 crosses. 14 images are an extra goody, not required. The idea is that, if you have the 14 images, they are images of scenes involving the cross, and so the images themselves depict crosses. It is not necessary to have 14 crosses and 14 images. (If you had some sort of strange abstract stational images which did not include crosses, I suppose that would be a problem.)
I don't see anything there about anything that is required to be blessed by a Franciscan. I think it's odd that an indulgence available to the whole church would be dependant on a blessing of a member of a particular religious order.
63. Exercise of the Way of the Cross (Viae Crucis exercitium)The Chuch I know of does not have the Stations legitimately erected...
A plenary indulgence is granted to the faithful, who make the pious exercise of the Way of the Cross.
In the pious exercise of the Way of the Cross we recall anew the sufferings, which the divine Redeemer endured, while going from the praetorium of Pilate, where he was condemned to death, to the mount of Calvary, where he died on the cross for our salvation.
The gaining of the plenary indulgence is regulated by the following norms:
1. The pious exercise must be made before stations of the Way of the Cross legitimately erected.
2. For the erection of the Way of the Cross fourteen crosses are required, to which it is customary to add fourteen pictures or images, which represent the stations of Jerusalem.
3. According to the more common practice, the pious exercise consists of fourteen pious readings, to which some vocal prayers are added. However, nothing more is required than a pious meditation on the Passion and Death of the Lord, which need not be a particular consideration of the individual mysteries of the stations.
4. A movement from one station to the next is required.
But if the pious exercise is made publicly and if it is not possible for all taking part to go in an orderly way from station to station, it suffices if at least the one conducting the exercise goes from station to station, the others remaining in their place.
Those who are "impeded" can gain the same indulgence, if they spend at least one half an hour in pious reading and meditation on the Passion and Death of our Lord Jesus Christ.
For those belonging to Oriental rites, amongst whom this pious exercise is not practiced, the respective Patriarchs can determine some other pious exercise in memory of the Passion and Death of our Lord Jesus Christ for the gaining of this indulgence.
By your own words (refering to the Enchiridion Indulgentiarum) you are incorrect...