Not really. Those are classified as "Half-Illithids", or "Half-Mind Flayers".
But at the same time, they remain members of the colony, which can still be useful. Brainstealer dragons sometimes ruled illithid settlements that did not have an elder brain.
A small variety of species could successfully undergo ceremorphosis, but if not from one of the fully compatible races, the result was called a "half-illithid", also known as a "ceremorph" or "flayer-kin". They do, however, still possess most of the powers of a regular Mind Flayer.
But I still don't understand what the problem is. The creation of new illithids (Or Half-Illithids) can help them build up their power and the upcoming battles.
Besides, the tadpoles in the brains of the protagonists (And True Souls) are different from those that were earlier. They are probably devoid of the previous flaws and may expose Ceremorphosis to a more extensive list of races. We cannot yet talk about their strength and capabilities.
By the way, the "new" parasites can infect Warforged. It will be more serious than halflings and kobolds.
