What practitioners hold is that attention directed to these centres produces reliable and reportable changes in experience, of energy, warmth, emotional release, absorption, and that a practitioner can work with those changes systematically. That much is a claim about first-person experience, and the experiences are real in the sense that people consistently report them under the described conditions.
The claims that go beyond this are where the disputes lie, and the disputes run inside the tradition as well as between it and outsiders.
Kundalini awakening is the most serious. Classical and modern sources alike warn that raising the energy without preparation or guidance can produce severe disturbance, what the literature calls kundalini syndrome, with reports of anxiety, insomnia, involuntary movement, heat, and in some cases episodes indistinguishable from acute psychiatric crisis. Traditional teachers treat that as a reason for lineage, initiation and supervision. Clinicians who have written on it regard some of the reports as spiritual-emergency presentations of underlying conditions. Both readings are in the literature and neither has displaced the other.
Medical claims are the second area. Chakra balancing is widely offered as a therapeutic service, and where it is presented as treatment for diagnosable illness the claim is testable and unsupported.
The third is a live argument about appropriation and accuracy. Indian practitioners and academic scholars of tantra have objected that the Western chakra system, with its rainbow, its glands and its self-help vocabulary, is presented as ancient Indian knowledge while differing substantially from the sources. Western teachers reply that traditions have always adapted. The historical facts underlying the argument are not themselves in dispute.