https://www.fda.gov/media/114912/download
Cynosure Device Forbidden for “Vaginal Rejuvenation” by FDA Class Action | Class Actions Reporter
and for recent research
Google Scholar
Note that most of the references will only give a summary not the full article. You will not be able to see details nor see if the manufacturer sponsored the work. Keep in mind that significant difference between groups may be statistical but not meaningful. Example. In group A of 100 patients 22 improved but in group B 15 improved. This is a statistical difference but is it clinically meaningful? What if the undesirable side effect rate is 5% in each group? Now of 100 patients in group A 22 get benefit, 73 see no change, and 5 get worse. In cancer care this might be a big win. In life-style therapy this is not a big win, but maybe a little one.
Do note that the FDA has warned the company selling this product to stop making undocumented claims. And that the company was sold at over 1 Billion dollars to a new distributor in the hopes that it would generate a lot of profit. Buyer beware.
You are wise to seek information on efficacy. However asking for testimonials on a website may not get you reliable information.