Are the "cotton candy" grapes kosher for consumption? I know Kashrut.com says they are kosher, but am wondering if one of the main organizations made a statement on them. (Not sure if the grape modification affects their kashrus status)
The link that you quote from Kashrut.com says that the Atlanta Kashruth Commision says that they are acceptable without any special certification. The above Hechsher is considered reliable by CRC's standards (here), so practically speaking, there is no issue with eating them.
However, if you want to know why they are considered Kosher, I will explain.
As per this article, Cotton Candy Grapes are the result of plant breeding (no genetic modification, no artificial flavoring). You can learn more about plant breeding at the link that they supply, but since there are no non-Kosher plants, this process avoids actual Kashrus issues.
And if you ask but it is possible that some of the plant crossing may qualify as Kilayim, take a look at Rambam Hilchos Kilayim 1:7 (Chabad.org translation), which states explicitly that any hybrid is permitted to be eaten, and even replanted in the future:
הזורע זרעים כלאים וכן המרכיב אילנות כלאים אף על פי שהוא לוקה הרי אלו מותרין באכילה ואפילו לזה שעבר וזרען שלא נאסר אלא זריעתן בלבד ומותר ליטע ייחור מן האילן שהורכב כלאים ולזרוע מזרע הירק שנזרע כלאים:
Although he is liable for lashes, when a person sows forbidden species together or grafts forbidden species of trees together, the produce that grows is permitted to be eaten, even by the person who transgressed and sowed it. For it is only sowing that is forbidden. It is permitted to plant a branch from the grafted tree or plant the seeds from a vegetable that was planted together with mixed species.
(In fact, many of the fruits and vegetables that we eat are hybrids.)