Never heard of this... Did your wife attend GCS earlier while she's still waiting for her visa? IF she did attend, then no need to re-do the seminar. She just needs to go directly in CFO office and present the GCS certificate that was given to her when she attended the GCS seminar.
It is not possible to skip the seminar and go directly to CFO just for the sticker as they will not find her name in their system. Every person who attended the seminar are recorded in their system where they will re-check in the CFO office once you presented the GCS certificate. No record in their system meaning you skip or did not attend the training... You will be asked to attend the seminar before they stamp the CFO sticker in your passport.