If these are AC to AC adapters that are just linear power transformers with no regulation then yes, the output voltage will be slightly higher than spec if there is no load on them, it's normal. You need to test them loaded with the circuit that you are trying to power. I would not use one that is rated above 15V max though.

I think similar to this? https://www.amazon.com/SupplySource-Adapter-PS1505ACU-Non-Regulated-Single-Voltage/dp/B07WHBQD3F