A dark bulbous root is most likely the hair and not the follicle itself. Give it a full year to evaluate your results and then I would speak with your physician about options.
Plucking Transplanted Eyebrows
After 7 months, it's likely that the eyebrows that you
plucked will grow back. Unfortunately, the only definitive way to know is by
waiting. If you don't see any new growth after several weeks, contact the
doctor who performed your hair transplant. He or she will be able to provide
you with guidance through the necessary next steps. Best wishes.
Its hard to say
if the hairs will grow back. At 7 months not all of the hairs that were transplanted have began to grow. Also keep in mind that transplanted hairs can grow in a little oddly at first. They will usually thicken and straighten after a few months. So don't start plucking them too soon.
Eyebrow plucking post transplant
Whether or not a 'plucked' hair grows back after a hair transplant depends on the precise timing that it was plucked out and where on the body is was plucked from. In general, an eyebrow hair that is plucked out more than 4 weeks after the procedure has an approximately 80-90% chance of coming back. If plucked out before that time, it's difficult to know if it will or not. Be sure to check with your hair transplant surgeon for definitive guidance.