I rather go to the side of caution, especially with cacti, I will reduce watering. Your gymno will have moisture in its ball, but to push the blooms it needs that consistent warmth and light. Outdoors is a bit easier for me, since our area hardly rains, and the cooler temps allows for more moisture in the air which succulents can use during their night time air exchange, so even if I do not water, it can get something from the cool air.
Your set-up is mostly indoors, so I will be careful of overwatering, so reduce it for now, that will be my suggestion. Put it in a well lighted area, maybe it may coax the plant to finally make a go and push those blooms out. If it is decided to sleep since it is not feeling that strong light anymore then wait for next season to continue your pollination experiment.
I always see that grafted cacti in our local stores, but have not tried it. Thank you for your thread..I may just try some this coming Spring to see how it will go on my side.
